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ANL-6262 Phys ic s AEG Research and Development Report
ARGONNE NATIONAL LABORATORY 9700 South Cass Avenue
Argonne , Ill inois
PHYSICS DIVISION SUMl^lARY REPORT
December I960
Morton Hame r m e s h , Division Di rec to r
Preceding Summary Repor t s :
ANL-6190 - July^ August I960 ANL-6214 - Sep tember , October I960 ANL-6235 - November I960
Operated by The Univers i ty of Chicago under
Contract W-31-109-eng-38
1
TABLE OF CONTENTS
The date of the last preceding r e po r t i s indicated after the t i t le of each project below. P ro j ec t s which a r e not r epor t ed in th is i s sue a r e l i s ted on subsequent pages .
I. EXPERIMENTAL NUCLEAR PHYSICS PAGE
I-10-1 TANDEM VAN DE GRAAFF ACCELERATOR (New project)
F . P . Mooring and J . R„ Wal lace . . . . . . . o . . . .
The operating pr inciple of the tandem Van de Graaff a c c e l e r a t o r i s d i scussed . The new tandem wing on Building 203 i s de sc r ibed .
1-11-26 INSTALLATION AND OPERATION OF THE VAN DE GRAAFF GENERATOR (ANL-6214, S e p t . - O c t . , I960)
J . R„ Wallace,
The use and operat ion of the 4 . 5 - M e v Van de Graaff genera tor i s desc r ibed for the per iod from July 1 to September 30, I960 .
1-14-21 PULSED BEAMS FOR THE VAN DE GRAAFF GENERATOR (ANL»5978, F e b . - A p r . , 1959)
R. E . Holland, F . J . Lynch, and E . N . Shipley 7
An upper l imit was set for the obse rved mean life of the f i rs t excited s tate of Ca ^ and a lower l imit was set for the pa r t i a l mean life for decay by E2 t r ans i t ion from the same s t a t e .
1-58-8 DELAYED NEUTRON GROUPS FROM N^'^ (ANL-5955, D e c . 1958, J a n . 195 9)
G. J . P e r l o w , A. F . Stehney (CHM), W. J . R a m l e r (CHM), and J . L . Yntema. . . . . . . . . . . 8
1 7 Groups of delayed neut rons f rom a N ^ ' p r e c u r s o r have been observed at energ ies of 1.225 and 0.425 Mev, c o r r e s ponding to |3 decay to _ s t a tes in O^''' in a g r e e m e n t with the shel l mode l .
1-116-1 PRINCIPLES OF C Y C H C PARTICLE ACCELERATORS
John J . Livingood (New project) 9
Designed for college s tuden t s , this text a s s u m e s no p r i o r knowledge of the subject and leads to a quanti tat ive unde r standing of the va r ious devices in which acce l e r a t i on i s produced by ac vo l tage . The emphas i s i s on pa r t i c l e dynarai c s .
MASS SPECTROSCOPY
II -40-7 FRAGMENTATION OF HYDROCARBONS (ANL-6169, June I960)
H. E . Stanton. 11
E a r l i e r invest igat ions of the f ragmentat ion of h y d r o carbons with h igh-energy e lec t rons w e r e extended to benzene and e thylene. The r e s u l t s indicated a dependence of fragment yield on bond energy .
PLASMA PHYSICS
I V - l O - i HIGH-FREQUENCY PLASMAS ,
Alber t A. Hatch (New project) 17
The p lasma r e s e a r c h p r o g r a m a t Argonne i s outlined and re la ted to the o v e r - a l l field of p l a s m a p h y s i c s . The major r e s e a r c h de sc r i be d is an exper imenta l study of bas ic p r o p e r t i e s of p l a s m a s produced in homogeneous high-frequency e l ec t r i c fields at low p r e s s u r e s . The minor r e s e a r c h de s c r i be d is a t heo re t i ca l study of the in terac t ion of p l a s m a s with nonhomogeneous h igh-frequency e l ec t romagne t i c f ie lds .
THEORETICAL PHYSICS, GENERAL
V-13-2 SPIN-ORBIT SPLITTING AND PION THEORETIC L-S POTENTIAL (ANL-6130, March I960)
Akito A r i m a , Masao Sugawara , and Tokuo T e r a s a w a . . 29
The doublet spl i t t ings in He^ , N^^ , and O^^ (closed shel ls plus or minus one nucleon) a r e adequately explained in t e r m s of the combinat ion of the s econd-o rde r effect due to the t ensor force and the f i r s t - o r d e r effect due to the L-S po ten t ia l .
i i i
PAGE V-42-1 GEOMETRIC THEORY O F CHARGE
H. Ekste in (New project) 34
The paper a t t empts to explain some bas i c p r o p e r t i e s of e l ec t r i c charge from space- t ime s y m m e t r y cons idera t ions a lone . As a surpr i s ing by -p roduc t , it is found that the assumpt ion of full space - inve r s ion symmet ry p red ic t s the kind of "par i ty nonconservat ion" effects that a r e usual ly considered to prove the absence of this s y m m e t r y .
PUBLICATIONS 44
PERSONNEL CHANGES IN THE ANL PHYSICS DIVISION 47
PROJECTS NOT REPORTED IN THIS ISSUE
A re fe rence to the las t preceding r e p o r t i s given in p a r e n -ses for each p ro jec t .
EXPERIMENTAL NUCLEAR PHYSICS
I - l - Neutron De tec to r s (ANL-6072, O c t . - N o v . , 1959), G. E . T h o m a s .
1-3- C r o s s Section M e a s u r e m e n t s with the F a s t Neutron Velocity Selector (ANL-6072, O c t . - N o v . , 1959), L . Boll inger and R. C o t e ' .
1-7- G a m m a - R a y Spect ra from Capture in Neutron Resonances (ANL-6146, A p r i l - M a y , I960) , L . M. Boll inger and R. T . C a r p e n t e r .
1-18- Different ial C r o s s Section for Neutron Resonance Scat ter ing (ANL-6169, June I960), Raymond O. Lane .
I "19- Nuclear Resonance Absorpt ion of Gamma Rays (ANL-6169, June I960), L . L . L e e , J r . , L . M e y e r - S c h u t z m e i s t e r , J . P . Schiffer, and D. Vincent .
1-22- Scat ter ing of Charged P a r t i c l e s (ANL-6130, March I960) , Jan Yntema, B , Ze ldman, T . H. Bra id .
1-28- Angular Cor re la t ions in C h a r g e d - P a r t i c l e React ions (ANL-5978, F e b . - A p r i l , 1959), T . H. B r a i d .
1-30- Decay of ^g^r^^^ (3 .1 hr) (ANL-6190, Ju ly-August , I960) , H. A. Grench and S. B . B u r s o n .
1-33- Decay of Tm^^^ (ANL-6235, November I960), S. B . Burson and R. G. H e l m e r .
1-43- Stopping Power of Carbon for Po^^° Alpha P a r t i c l e s (ANL-6235, November i960) , S. B a r k a n .
1-44- Branching Ratio of a and P E m i s s i o n from Bi-212 (ThC) (ANL-6235, November I960) , S. B a r k a n .
1-55- Capture G a m m a - R a y Spect ra for Neutrons with E n e r g i e s f rom 0 .1 to 10 ev (ANL-6052, Sep tember 1959), Sol Raboy and C a r r o l l C. T r a i l .
1-60- 7 . 7 - M e t e r Bent=Crys ta l Spec t rome te r (ANL-6235, November I960), Rober t S m i t h e r .
1-80- Molecular B e a m Studies (ANL-6214, Sept . - O c t . , I960) , Leonard S. Goodman and W. J . Ch i lds .
m
v
1-90- Cros s Sections for 14-Mev Neutrons (ANL-6072, Oct . - N o v . , 1959), Harvey Casson and L. A. Rayburn.
1-98- Neutron Total C r o s s Sections in the Kev Region (ANL-6235, November i960) , Ca r l T . Hibdon.
1-102- Neutron Cross Sections by Self-Detection (ANL-6214, Sept. - O c t . , I960), J a m e s E . Monahan.
I - l l O - Storage of Pulse-Height Data on Magnetic Tape (ANL-6072, O c t . -Nov . , 1959), J a m e s B a u m g a r d n e r .
I - I U - Sol id-s ta te Radiat ion De tec to r s (ANL-6235, November I960) , T. H. Bra id and J . T. Heinr ich .
1-144- Investigation of Scint i l la tors (ANL-6235, November i960) , W a r r e n Buck, Louis Bas i l e . and R. Swank.
MASS SPECTROSCOPY
11-18- Lead Ages of Meteor i tes (ANL-6169, June i960) , D. C. H e s s .
11-28- Kinet ics of Chemical Reac t ions in the Gas P h a s e (ANL-58 i8 , Oct . -D e c , 1957), Will iam A. Chupka.
11-29- Gaseous Species in Equi l ibr ium a t High T e m p e r a t u r e s (ANL-6105, January I960), Wm. A. Chupka.
11-34- A ^ ° - K ^ ° Dating of Meteor i tes (ANL-6 i90 , J u l y - A u g . , I960), David C. H e s s .
11-38- Mass Spec t rome t r i c Study of Charged Atomic and Molecular P roduc t s of Nuclear Trans fo rmat ion (ANL-6214, Sept . - O c t . , I960), Sol Wexler .
CR YST ALLOGRAPHY
I I I -4 - Crys ta l S t ructure Studies of Compounds of E l emen t s A c - A m (ANL-6038, Ju ly-Augus t , 1959), Wm. H. Z a c h a r i a s e n .
I I I - IO- The Crys ta l S t ruc ture of lui^Y/O^ (ANL-6169, June I960) , H. A. Ple t t inger and W. H. Z a c h a r i a s e n .
V. THEORETICAL PHYSICS, GENERAL
V - 3 - Dynamics of Nuclear Collective Motion (ANL-6214, Sep tember -October , I960) , David R. Inglis and Kiuck Lee .
V - 8 - Relat ionships of Collective Effects and the Shell Model (ANL-6235, November I960), Kie ter Kura th .
V - 1 5 - Sta t i s t ica l P r o p e r t i e s of Nuclear Energy States (ANL-6088, December 1959), Norber t Rosenzweig .
V - 1 8 - E l emen ta ry P a r t i c l e s in DeSi t ter Space (ANL-60 38, Ju ly-August , 195 9), Will iam C. Davidon.
I - l O - l
I . EXPERIMENTAL NUCLEAR PHYSICS
I - l O - l Tandem Van de Graaff Acce le ra to r (51210-01)
F . Paul Mooring and Jack R. Wallace Reported by Jack R. Wallace
A new r e s e a r c h tool will soon be in use by the menmbers of
the Van de Graaff Section of the Phys ics Division. It is the 12-Mev Tandem
Van de Graaff Acce le ra to r designed and built by High Voltage Engineer ing
Corpora t ion , Burl ington, M a s s a c h u s e t t s .
The tandem a c c e l e r a t o r design has evolved d i rec t ly from
that of a conventional Van de Graaff e l ec t ros ta t i c g e n e r a t o r . A Van de
Graaff e lec t ros ta t ic acce l e ra to r has cer ta in advantages in invest igat ion of
the p roper t i e s of the nucleus . Some of these a r e : (1) This type of accel=
e ra to r i s capable of producing a t ightly col l imated b e a m of charged pa r t i c l e s
(2) The energy of the pa r t i c l e s emerging from such an a c c e l e r a t o r can be
va r i ed continuously over a l a rge range . (3) The energy sp read of these
pa r t i c l e s can be kept very sma l l ( a 0 .05%).
The tandem a c c e l e r a t o r ' s method of achieving higher
par t ic le energies from the s a m e t e r m i n a l voltage became poss ib le when
sc ien t i s t s learned how to produce nega t ive ly-charged hydrogen ions (p ro
tons to which two e lec t rons have been a t t a c h e d ) . The pr inc ip le of a tandem
acce l e r a to r is to produce an in tense beam of p r o t o n s , a c c e l e r a t e them by
passing them through a potent ial drop of about 40 k v , then pas s them through
hydrogen gas where they pick up two e l ec t rons . Th is source of negative
ions i s ex terna l to the Van de Graaff a c c e l e r a t o r and at ground potent ia l ,
but connected to i ts acce le ra t ion tube . These negative ions a r e a c c e l e r a t e d
from ground to the high-voltage t e r m i n a l which is charged to a posit ive
I - l O - l
voltage (1 to 6 mil l ion vo l t s ) . In fliis high-voltage shel l these ions a r e pas sed
through a gas cel l which r emoves the two e lec t rons and changes the charge
of the ion f rom negative to pos i t ive . They a r e again a c c e l e r a t e d by pass ing
through another acce le ra t ing tube col l inear with the f i r s t , which runs froiri
this t e r m i n a l shel l to ground. So in this way the pa r t i c l e has acqu i red an en
ergy twice that a s soc i a t ed with the potential difference of the t e r m i n a l voltage
and ground. The emerging protons a r e then p a s s e d through a 90° magne t ic
ana lyzer whose magne t ic field i s ve ry carefully s tabi l ized and control led . A
signal from the output s l i t s of th is magnet ic ana lyzer i s used to s tabi l ize the
voltage of the t e r m i n a l shel l of the t andem. The pro tons p roceed to a swi tch
ing magnet which can d i r e c t them to the va r ious p ieces of exper imenta l equip
ment located in the t a r g e t a r e a .
The tandem gene ra to r will p e r m i t a logical extension of ce r t a in
m e a s u r e m e n t s and invest igat ions now being c a r r i e d on a t our p r e s e n t Van de
Graaff a c c e l e r a t o r . New exper imen t s will a l so be poss ib le at these higher
energ ies now avai lable with the t andem. M e m b e r s of the Phys i c s Division a r e
now planning and designing exper imenta l equipment for use with th is new
a c c e l e r a t o r .
The plan view of the exper imenta l level (F ig . 1 ) of the new t a n
dem wing of building 203 shows the location of the a c c e l e r a t o r , ana lyzer
m a g n e t s , and switching m a g n e t s , and the re la t ive s izes of the va r ious a r e a s .
The plan chosen will allow a max imum usefulness of the t andem. The e m e r g
ing ion beam from the t andem can be d i rec ted through e i ther of the 90° magnet ic
ana lyze r s and then through a switching magnet which in tu rn d i r ec t s the b e a m
through any one of the five poss ib le be a m lines located in the t a r g e t a r e a s .
This m e a n s that while a given expe r imen t i s being conducted in one t a r g e t a r e a
the other t a rge t a r e a wil l be free of radia t ion and the re fo re the next exper imen t
can s imul taneously be p r e p a r e d and i t s equipment checked. Each t a rge t a r e a
has a da t a - r eco rd ing r o o m as soc ia t ed with it and t h e r e a r e wi reways provided
to c a r r y signal cables between the two a r e a s . E n t r a n c e into the vault and t a rge t
I - l O - l 3
a r e a while an experiment i s in p r o g r e s s will be control led. Doors and
gates through the radiat ion shield will be in ter locked, and radiat ion de tec
tion equipment will be instal led to monitor the a r e a s at a l l t i m e s .
The c ro s s section through the t a rge t a r e a s (Fig . 2) c lea r ly
shows the radiat ion shielding of the vault and ta rge t a r e a s , necess i ta ted by
operat ions at these ene rg i e s . The gamma cave in the eas t t a rge t a r e a is a
specia l room provided for exper iments that r equ i re a very low external
LOW LEVEL GAMMA CAVE-{ 14' X 16'
BEAM CATCHER, RECESS
EAST TARGET AREA
(50' X 50')
BEAM CATCHER RECESSES
CONSTRUCTION BUILDING
LOADING " PLATFORM
Fig . 1. Exper imenta l level plan view
(basenaent)
I - l O - i
MECHANICAL ROOM
EARTH EMBANKMENT
EAST TARGET AREA
BEAM CATCHER RECESS
WEST TARGEr AREA
GAMMA CAVE VAULT
I. i I., . I 0 10 20'
EARTH EMBANKMENT
BEAM CATCHER RECESS
Fig , Z. Cross section through target a r e a s .
DN.
^<':,...:^^-...BpkAi
-UPPER PART~ EAST TARGET
AREA
rf ' » f : " p " , i
-MECHANICAL ROOM-COMPRESSOR
GAS STORAGE
m^%:.,f;ji-..,di^'^';^ij.'":r^
UPPER PART-WEST TORGET
AREA
l„,.l.„,l,,„l,,.,l 0 10' 20' CONSTRUCTION BUILDING
Fig , 3 . Service level plan view (1st floor)
background. The m a t e r i a l s used in the concrete of the wa l l s , cei l ing, and
floors of this room have been selected for a minimum content of r a d i o
act ive e l emen t s .
The plan view of the serv ice level (Fig, 3) shows the
a r e a above the vault in which the acce le ra to r is located. It will contain
I - l O - l 1-11-26
5
the a c c e s s o r y equipment for the t andem, such a s c o m p r e s s o r , gas s to rage
t anks , gas d r i e r , gas r e c i r c u l a t o r , m o t o r - g e n e r a t o r s e t s , vacuum pump,
power dis t r ibut ion pane l , e t c . The se rv ice ga l le ry a r ea will contain heating
and ventilating equipment , a dis t r ibut ion sys tem for signal and control wi re , ,
and eventually th ree offices on the west s ide .
The p resen t construct ion schedule ca l ls for the tandem wing
to be conapleted June 15, 1961. High Voltage Engineering schedules our t an
dem for completion by May 1961. It i s hoped that the tandenn's instal la t ion
will not r e q u i r e more than 3 months after i ts de l ivery to our s i t e .
1-11-26 Instal la t ion and Operat ion of the Van de Graaff Genera to r (51210-01)
J . R. Wallace
This r epo r t covers the operat ion of the Van de Graaff g e n e r a
to r in the Phys i c s Division for the per iod from July 1 to September 30, I960
inc lus ive .
T h e g e n e r a t o r w a s u s e d to a c c e l e r a t e p r o t o n s and a l p h a s .
I ts voltage va r i ed from 1.6 to 4 . 4 Mv. The beam c u r r e n t s m e a s u r e d . a t the
t a r g e t va r i ed from 0.1 to> 30 ^ a .
The following l is t shows the type of exper imen t s pe r fo rmed
with the genera tor and the number of hours per exper iment .
1. Neutron polar iza t ion
2. Resonance f luorescence
5 9
3. Total c r o s s section of Co and of N^^
" 5 7
4. Mossbauer effect in Fe by Coulomb excitat ion
Elwyn, Lane 9 . 6 h r
H e b e r l e , Meye r , ^ . emman
Huddleston, ^^ . . ' 264.4
Mooring
Holland, Lynch ^08 . 8
1-11-26
4 0 .
155.
37 .
4 8 .
791 .
4 3 .
365.
1200.
,3 hr
,0
,6
2
,3
,0
,7
, 0 hr
5 . Calibrat ing neutron survey counter Anderson
6. Tota l c r o s s section in kev region Hibdon 2 3 6
7. F i s s ion c r o s s section of U Stupegia 4 8
8. Po l a r i z ed protons from Ti (d,p) S m i t h e r , Weinman
Star tup and daily main tenance
Machine r e p a i r s and expe r imen ta l setup
Total t i m e avai lable (64 days X 16 h r + 22 days X 8 h r )
We a r e now trying in the Van de Graaff gene ra to r a c h a r g e -
car ry ing bel t f rom Fab reeka that has a longer lap joint . It was bel ieved by
thei r engineers that the re la t ive ly sma l l d i ame te r (6 i n . ) of our dr ive pulley
caused m o r e than no rma l flexing of the bel t a t the lap joint . In addition to this
flexing we have conditions (high l ineal be l t speed plus high gas density) that
lead to unusual ly high wind ac t ion on the lap joint in the b e l t . Since the
fa i lures with th is bel t have been exclusively at the l ap , we hope this change
in lap design m a y improve the life of the be l t .
T e s t s with F a b r e e k a endless wrapped bel t have been u n s a t i s
factory so f a r . The different method of cons t ruc t ion neces s i t a t ed by th i s
type of bel t in t roduced undes i rab le fea tures for our appl ica t ion.
We were plagued with an i r r e g u l a r pulsing be a m which caused
much unsa t i s fac tory operat ion during th is pe r iod . The cause of th is t rouble
was an i n t e rna l e l ec t r i c a l leakage path (low r e s i s t a n c e path) in the insulating
d r ive pulley of the 400-cycle genera to r in the high-vol tage shel l of the Van
de Graaff a c c e l e r a t o r . This i r r e g u l a r leakage caused fluctuations in the
charge r e m o v a l f rom the charging be l t and r e su l t ed in energy changes of the
beam a t the t a r g e t .
Additional t ime was lost during th is q u a r t e r because of a
breakdown of our a i r c o m p r e s s o r u s e d for gas t r a n s f e r .
1-14=21
I-14-21 Pulsed Beams for the Van de Graaff Genera to r (51210-01)
R. E . Holland, F . J . Lynch, and E . N. Shipley Repor ted by R„ E . Holland
PARTIAL LIFETIMES OF FIRST EXCITED STATE OF Ca*^
1 Because of r ecen t i n t e r e s t in the l i fet ime of the f i r s t exci ted
4 3
state of Ca , we began a meas \ i r emen t of th i s l ifetime by a pu l sed -beam 2
technique. While the work was in p r o g r e s s , we l ea rned of a completed 3
m e a s u r e m e n t by Schwarzchi ld and co l l abora to r s at Brookhaven. Our m e a s -
u r e m e n t s indicate that the mean life i s l e s s than 0. 1 m |xsec , in a g r e e m e n t
with an upper l imit of 0,06 mjxsec es tab l i shed at Brookhaven.
During this work , we a l so observed that this s ta te was not
strongly excited by a -pa r t i c l e bombardment (the m e a s u r e m e n t desc r ibed above
was made by proton bombardment ) , and the re fore that the c r o s s sect ion for
Coulomb excitation was sma l l . We were able to es tab l i sh an upper l imit for
the c r o s s section by comparing the yields of gamma r ays from thick t a r g e t s 4 3
of CaCOg(23% Ca ) , CaCOg (no rma l ) , and V (normal ) . No gamma r a y s of
374-kev were observed from ei ther Ca t a rge t under bombardment by 3 , 2 -1 8 2 1
Mev a p a r t i c l e s . Gamma r a y s of 342 kev from O (a ,n )Ne produced a
background which allowed us only to es tab l i sh that the number of 374-kev 4 3
gainma rays from the Ca t a rge t was less than 4% of the numiber of 323-kev 4
ganama rays from the V t a rge t . Using the value B ( E 2 ) = 0.0056 b a r n
1
T. Komoda, submitted for publicat ion in P r o g r e s s of Theo re t i ca l Phys i c s (Kyoto). 2
R. E . Holland and F . J . Lynch, P h y s i c s Division Summary R e p o r t , ANL-5955, (December , 1958, J a n u a r y , 1959), p« 3.
P r iva te communicat ion.
K. A l d e r , A. Bohr , T . Huus , B . Mot te l son , and A, Winther , R e v s . Modern P h y s . 28 , 432 (1956).
1-14-21 1-58-8
5 1
for the reduced E2 t rans i t ion probabi l i ty for V and cor rec t ing for the
difference in energy of the gamma r a y s and the difference in stopping power
of the t a r g e t s , we find for the reduced t r ans i t ion probabi l i ty for f i rs t excited 4 3
state of Ca
B(E2) < 0.000248 b a r n s .
The corresponding l imit on the pa r t i a l E2 mean life i s
T (E2 ) > 34 m|x sec .
We infer that the shor t observed l ifet ime i s due to a high p a r t i a l t r ans i t ion
r a t e for Ml decay .
1 7 1-58-8 Delayed Neutron Groups from N (51210-01)
G. J . P e r l o w , A . F . Stehney (CHM), W. J . R a m l e r (CHM), and J . L . Yntema
The energy of the neut rons which follow the p -decay of i r 1
4. 1-sec N was m e a s u r e d by m e a n s of a neut ron spec t rome te r in which
the energ ies of proton r eco i l s were de t e rmined in a t r ip le p ropor t iona l -
counter a r r a n g e m e n t . The energy ca l ib ra t ions were made with monoenerget ic 7 7 1 7
neutrons from Li (p ,n )Be at the Van de Graaff g e n e r a t o r . The N was 1 4 17
produced in the reac t ion C ( a , p ) N at a mean energy of about 25 Mev, The 1 4
C was in the fornn of a 14-mg pel le t of 41% en r i chmen t , sandwiched in
aluminuin foil. Bombardment and counting were a l t e rna ted by shut ter ing
1
G. J . P e r l o w , Rev . Sc i . I n s t r . 27 , 460 (1956).
1-58-8 1-116-1
the cyclotron b e a m . Two groups of neut rons were obse rved with ene rg ies of
1.225 ± 0.060 and 0.425 ± 0,020 Mev and re la t ive in tens i t ies in the ra t io
l , 6 r l . Within a smal l energy d i sc repancy , these co r re spond to (3 t r ans i t ions 3 _ 1 7
to the 2 s tates of O at 5,38 Mev and 4. 56 Mev. The h igher energy neut rons 2
reported by Hayward would not have been observed. 1 7 , ,
A paper enti t led "Delayed Neut rons from N has been p r e pa red for publication.
2 E . Hayward, P h y s , Rev. 7 5 , 917 (1949).
1-116-1 P r inc ip l e s of Cyclic Pa r t i c l e A c c e l e r a t o r s (51210-01)
John J , Livingood
This book p r e s e n t s a coherent d i scuss ion of existing v a r i e t i e s
of cyclic par t ic le a c c e l e r a t o r s ; cyc lo t rons , synchrocyc lo t rons , s y n c h r o t r o n s ,
b e t a t r o n s , m i c r o t r o n s , sec to r - focused dev i ce s , l inear a c c e l e r a t o r s , and
s tochast ic m a c h i n e s . These a r e desc r ibed in sufficient de ta i l to show the i r
s i m i l a r i t i e s , d i f ferences , and l imi ta t ions .
The p rob lem of orbi t s tabi l i ty r e c e i v e s e m p h a s i s , with d i s
cuss ions of weak- , s t r o n g - , and sec tor- focusing techniques and of the means
of calculating the frequencies of the a s soc i a t ed osci l la t ions of the o r b i t s .
The important concepts of momentum compact ion , phase s tabi l i ty , and syn
chrotron osci l la t ions a r e desc r ibed and ana lyzed , and ce r t a in p rob lems of
injection and ejection a r e cons ide red .
The t r e a t m e n t follows the development of a c c e l e r a t o r s from
the s impler to the more complex . An unini t ia ted r e a d e r (who i s a s s u m e d to
unders tand the calculus) i s led through the advances which have o c c u r r e d
over the y e a r s , up to the point where he has gained a solid unders tanding of
1-116-1
the underlying p r inc ip les and has become equipped to r ead intel l igently
the many a r t i c l e s on the subject which appear in the scientif ic j o u r n a l s .
The book, of approximate ly 370 p a g e s , i s i l lus t ra ted with
136 drawings and 28 photographs . A bibl iography of about 500 i t ems is
a r r a n g e d by type of a c c e l e r a t o r , a s an aid in co l l a t e ra l reading for those who
inay wish to delve deeper into theo re t i ca l a spec t s or to l e a r n construct ional
de ta i l s of pa r t i cu la r in s t a l l a t ions .
The D. Van No s t rand Company expects to r e l e a s e the
volume in June 1961.
I I -40-7 11
II . MASS SPECTROSCOPY
II-40-7 Fragmenta t ion of Hydrocarbons (51300-01)
H. E . Stanton
The e a r l i e r invest igat ions of the f ragmentat ion of h y d r o c a r
bons under impact by e lec t rons with energ ies ranging up to a few ki lovolts were
extended to benzene and e thylene . The exper imenta l a r r a n g e m e n t s and t e c h
niques of m e a s u r e m e n t s were ident ica l to those used for neopentane and h e p
tane which were repor ted e a r l i e r .
The r e s u l t s for benzene a r e shown in F i g , 4 . In F ig , 4 ( a ) ,
the conaparison of the m a s s spec t rum given by MA-17 and the one given in
P ro jec t 44 of the A m e r i c a n P e t r o l e u m Inst i tute (used a s a s t anda rd ) , for an
e lec t ron energy of 70 ev , shows the usxxal p r o g r e s s i v e d i s c r epanc i e s in r e
lative yield for the lower m a s s n u m b e r s , but o therwise shows a reasonab le
a g r e e m e n t , except for m a s s 15. The r eason for the g r e a t difference
(amounting to a factor of 10) i s not known, and quite poss ib ly may be pa r t i a l
fai lure of r e sponse in MA-17, The yield for this peak fluctuated r a the r
badly throughout the exper imen t s and any conclusions with r e g a r d to yields
at m a s s 15 would be highly hypothet ica l . The yie lds were a l l no rmal i zed
re la t ive to the yield of the pa ren t ion at m a s s 78 , the l a r g e s t peaJs.
One n o t e s , a s with the a l i pha t i c s , that the re la t ive yield
usual ly shows a p r o g r e s s i v e d e c r e a s e with increas ing energy of the ionizing
e l ec t rons and with decreas ing m a s s n u m b e r . The d e c r e a s e s appear to be
m o r e nea r ly uniform and sonnewhat m o r e pronounced with benzene than
they were with heptane and neopentane . With the l a t t e r molecu les the re
were p r e f e r r e d modes of molecu la r rup tu re between adjacent carbon a t o m s ,
whereas the modes in benzene a r e l e s s obvious , poss ib ly because of the ring
s t ruc tu re and the t ighter binding between the carbon a t o m s .
1
Phys ic s Division Summary Repor t ANL-6169 (June I960) , p . 5 1 ,
+ 2
A i^ ^ M ^ 4.\ \
fsl
\ \ \
M 2 K
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(n UJ
- -2 UJ
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^ \ * \ c \ \ k ^ ^ N
^N 1^ \
FN
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L \ ft ^ N ^ ffl ^
26 27 37 375
38 39 49 50 51 52 61 62 63 73 74 75 76 77 78 79
B
PI n / ^ n
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7 / \ / \ / \
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^AlW n;. Nf^ ki
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s
/s /s /
15 26 27 3 7 , ^ ^38 39 37.5 49 50 51 52 61 62 63 73 74 75 76 77 78 79
MASS NUMBERS
4(a). Mass spectrum of benzene bombarded by 70-ev electrons. The right-hand peak at each mass number is the result obtained by MA-17. These are to be compared with the left-hand peaks, taken as standards, which were found at the Bureau of Standards and reported in Project 44 of the American Petrolexun Institute. Ordinates are the logarithms of the relative yields normalized to 100 for mass 78. (b) The mass spectra obtained from MA-17 for benzene at electron energies of 70 ev (left members) and at 2400 ev (right members). Both spectra were normalized to 100 at mass 78.
II-40-7 13
+2
> 0
z UJ
" - 2 UJ >
< - I UJ Q:
o 0
- 2
N
^
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^
Id
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y
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7
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12 13 14 15 24 25 26 27 28 29
/
/
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1/
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\
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UN N / \ / \
7
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FT / \ / \ / \ / \
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A. 12 13 14 15 24 25 26 27 28 29
MASS NUMBERS
Fig . 5 (a). Comparison of the m a s s spec t rum of ethylene a s obtained on MA-17 with 70-ev e lec t rons with a spec t rum given in P ro jec t 44 of the Amer ican Pe t ro leum Insti tute for e lec t rons of the same energy, (b) Comparison of the m a s s spec t ra obtained with bombarding energies of 70 ev (left) and 2400 ev (right) for e thylene. All peaks were normal ized to 100 at m a s s 28.
I I -40-7
The compar i son of the m a s s s p e c t r a , shown in F i g . 5 (a) ,
for ethylene a s given by MA-17 and P ro j ec t 44 , r e spec t ive ly , shows that
the d i sc repanc ie s a r e sma l l e r than in any other molecule examined so far
(probably because of the much sma l l e r range of m a s s n u m b e r s r equ i r ed ) .
However the genera l t r end in the differences a p p e a r s to be the usxial one.
The peak yie lds were again no rma l i zed with r e s p e c t to the p a r e n t , m a s s
28+ .
The m a s s spec t r a shown in F i g . 5 (b), tciken on MA-17
with bombardmen t energ ies of 70 ev and 2400 ev , indicate a somewhat J ,
g r e a t e r reduct ion in re la t ive peak intensi ty for m a s s e s 25 and lower than
for the other mo lecu le s . In con t r a s t , the re la t ive in tens i t i e s of m a s s e s
26 and 27 with r e s p e c t to the paren t peak did not change a s m a r k e d l y .
The changes in re la t ive yield for these two peaks were not m o r e than 25%
throughout the range of e l ec t ron ene rg ie s employed. The logar i thmic
a b s c i s s a t e n d s , unfor tunately , to obscure changes of th is o r d e r .
The r e s u l t s obtained up to th is point indicate a r a t h e r s imple
i n t e rp re t a t i on . The reduct ion in r e la t ive yield of a given ionic spec ies
with r e s p e c t to i t s pa ren t ion (or p r inc ipa l f ragment in the c a s e of neopentane)
under h igh-energy e lec t ron ic impac t a p p e a r s to be s imply c o r r e l a t e d with the
bond energy which mus t be b roken to produce i t . While , at th i s point , the
re la t ionsh ip i s only qua l i ta t ive , one notes for n-heptane that the re la t ive
yield of the p r inc ipa l peaks (85 , 71 , e t c ) changes l i t t le in going from +
70-ev to 2400-ev e l e c t r o n s , but the peak a t m a s s 15 a p p e a r s to be g rea t ly
changed. Although many of the f ragments der ived from these p r inc ipa l
peaks by success ive elinaination of hydrogens show minor changes a s a func
tion of e l ec t ron ene rgy , t h e r e a r e some exceptions: 84"*°, 69'*', 28 , and 26"^.
It a p p e a r s that the format ion of these peaks r e q u i r e s the break ing of a m o r e
energe t ic bond than does the r e m o v a l of a second hydrogen from a sma l l e r
f ragment . Since the C-C single bond i s about 3.5 ev and the s imple C-H
bond around 4 . 3 ev, the e a r l i e r experin:ients did not d is t inguish between
these two v a l u e s .
But on considering the p resen t r e s u l t s , F i g s . 4 and 5 , the
effect of bond energy becomes c l e a r e r . All the peaks in benzene for
m a s s number 63 and below (except the e r r a t i c peak at m a s s 14) showed a
comparat ively large drop in re la t ive yield as the bombarding energy of the
e lec t rons was i n c r e a s e d . The formation of these peaks involved the rup tu re
of at least one C-C bond with an energy of about 5.2 ev. Actually m o r e en
ergy was involved since production of a fragment involves not only breaking
the ring but a lso r e l e a s e from the r ad ica l so fo rmed . A s imi la r s ta tement
applies for ethylene since the formation of f ragments with m a s s e s 15 and
below requ i r e s the rup ture of a double bond with an energy of about 6. 3 ev.
Again in both m a s s s p e c t r a , the r emova l of one or two hydrogens from the
molecule does not seem to be ve ry sensi t ive to e lec t ron energy; but a s
m o r e hydrogens a r e r emoved , fur ther r e m o v a l becomes re la t ive ly l e s s
probable as the e lec t ron energy i n c r e a s e s .
T h e r e were t h r ee peaks that showed dis t inct h igh-energy
components and o thers that gave strong indicat ions of some kinet ic energy
of formation. At the lower e lec t ron e n e r g i e s , the m a s s - 1 5 ion from
benzene showed a well r e so lved peak at high kinet ic e n e r g i e s , with a m a x i
mum at 2 .3 ev, a width at half m a x i m u m of about 0 .5 ev , and an ampli tude
of about two th i rds of the ampli tude of the peak at t h e r m a l ene rg ies for
the same m a s s . This ion can be formed from benzene only by an extensive
r e a r rang emient, since the C H . r ad ica l i s not a p a r t of the s t r uc tu r e of the
parent molecu le . The re r e m a i n s the poss ib i l i ty that an impur i ty was
responsible for the peak, but this s eems doubtful.
Ethylene gave two peaks with h igh-energy p a r t s . One , at
m a s s 14''', which r e p r e s e n t e d a rupture of the double bond, had a m a x i m u m
at about 2 ,5 ev and a width a t half max imum of about 1.5 ev , but v e r y low
intensi ty . It s e e m s unlikely that this is a spur ious r e su l t caused by a
ni t rogen impur i ty . +
The ethylene f ragment peak at m a s s 13 a lso showed a sma l l
6 II-40-7
unreso lved h igh-energy component with a max imum around 2 ev. F ina l ly ,
the peak at 12"*" had a h igh-energy t a i l which indicated some kinet ic en
e rgy of format ion . It s e e m s probable that when the fragmentat ion of
ethylene involves the separa t ion of the two carbon a toms the re i s some
kinet ic energy of format ion .
IV-10-1 17
IV. PLASMA PHYSICS
IV-10-1 High-Frequency P l a s m a s (54100-01)
Albe r t J . Hatch
The purpose of this r e p o r t is to outline the p la sma r e s e a r c h
p r o g r a m at Argonne and to show i ts re la t ion to the o v e r - a l l field of p lasma
phys i c s .
There a re two l ines of r e s e a r c h being followed, one m a j o r ,
the other minor . The major r e s e a r c h i s an exper imenta l study of b a s i c
p roper t i e s of l ow-pres su re p l a smas produced in high-frequency e lec t r i c fields
which a r e approximately uni form in space in the absence of p lasma . Most of
the work to date has been on the high-frequency p lasmoid phenomenon. The
minor r e s e a r c h i s a theore t i ca l study of the in terac t ion of p l a smas with non-
homogeneous high-frequency e lec t romagne t ic f ie lds , with specia l emphas i s
on rf containment of p l a s m a s .
OSCILLATORY PHENOMENA IN PLASMAS
A plasma is a dynamic physical sys t em made up of e l e c
t r o n s , ionSjand neutra l gas a toms (or molecules) in which the e lec t ron and
ion densi t ies a r e usual ly approximate ly equal . The fraction of ionizat ion _ 8
can extend from as low as about 10 for weakly ionized p l a s m a s to a lmos t
1 for fully ionized p l a s m a s . The c h a r a c t e r i s t i c s of a p l a sma which d i s
t inguish it from other physical s y s t e m s a r i s e mainly from two c l a s s e s of
phenomena that involve both the individxial and the collective behavior of
the p lasma const i tuents .
One c lass of phenomena is the s ho r t - r a nge in te rac t ions
between the individual const i tuents of the p l a s m a , especia l ly between the
e lec t rons and a t o m s . These in te rac t ions include s h o r t - r a n g e h a r d - s p h e r e
e las t ic col l i s ions , ine las t ic co l l i s ions , recombina t ion , e lec t ron a t t achment .
IV-10-1
and in terac t ion with solid s u r f a c e s .
The other c lass of phenomena i s the individual and col
lective r e sponse of the e lec t rons and ions to long-range e l ec t r i c and m a g
netic f o r c e s . These forces may or ig inate e i ther from externa l ly applied
fields or from the in t e rna l collective behavior of e l ec t rons and ions t h e m
se lves . Among the phenomena included in th is c l a s s a r e the t r a n s m i s s i o n
and ref lect ion of e lec t romagne t ic radia t ion through p l a s m a s , containment of
p l a smas by magne t i c and e lec t romagne t ic f i e lds , and seve ra l spec ies of
e lec t ron and ion osc i l l a t i ons , including cyclo t ron r e s o n a n c e . It i s to th i s
c lass that the p lasmoid and containment phenomena belong.
P l a s m a - e l e c t r o n osc i l la t ions a r e one of the long-range
force phenomena which have been the subject of much r e s e a r c h s ince the i r
d i scovery over 30 yea r s ago . Tonks and Langmuir showed in 1929 that
these osci l la t ions occur in a one-d imens iona l sys tem at the r ad ian frequency 2 V^
w = (ne /mtQ ) , where n - e lec t ron dens i ty , e and m a r e the charge
and m a s s of the e lec t ron ,and Cg i s the pe rmi t t iv i ty of f ree space . Such
osci l la t ions in dc-or pu l se -exc i ted p l a s m a s r e s u l t from charge densi ty
g rad ien t s ; in rf*excited p l a s m a s they r e su l t from a combination of o sc i l l a
ting charge densi ty g rad ien t s and r e s p o n s e to the rf exci ta t ion. F o r the
range of e lec t ron dens i t ies no rma l ly encountered in l abora to ry p l a s m a s ,
the f requencies of p l a s m a - e l e c t r o n osc i l la t ions a r e in the nonainal range
of 1 to 10 000 M c / s e c .
Most of the expe r imen ta l r e s e a r c h on p l a s m a - e l e c t r o n
osci l la t ions has been pe r fo rmed in dc=excited plasnnas, a spec ies of p l a s
ma which i m p o s e s seve re l imi ta t ions on many (but not all) types of such o b -
s e r v a t i o n s , main ly because the osci l la t ions a r e m e r e l y a by-produc t of the
1
L . Tonks and I . Langmui r , P h y s . Rev . 33 , 195(1929) .
IV-10-1 19
more prominent dc p lasma m e c h a n i s m s . One is therefore justified in
the conjecture that th is is a situation which has perhaps ser ious ly hampered
the advance of our knowledge of osc i l l a to ry phenomena in p l a s m a s . Indeed,
it i s genera l ly recognized that p lasma osci l la t ions a r e cu r ren t ly one of the
least unders tood of the impor tan t bas ic phenomena of p lasma behavior .
It i s axiomatic in physics that the study of the osc i l l a to ry
p roper t i e s of a physical med ium can usual ly be pe r fo rmed mos t expedit iously
by exciting the medium at frequencies in the vicini ty of i ts r esonan t a n d / o r
cutoff f requencies . Thus one is led to expect that phenomena involving e lec t ron
oscil lat ions should become ve ry p rominen t , pe rhaps even dominant , in p l a s
mas excited by frequencies in the megacycle r a n g e . This expectat ion a p p e a r s
to be at leas t par t i a l ly confirmed by the many types of unusual phenomena
observed in r f -exc i ted p l a smas a t low p r e s s u r e s . F u r t h e r confirmation is
emerging from the detai led exper imenta l study of t he ' i n t e rna l c h a r a c t e r i s t i c s
of the var ious phenomena.
HIGH-FREQUENCY PLASMOIDS
There a r e t h r ee major p lasma m e c h a n i s m s which occur
in high-frequency p l a smas at low p r e s s u r e s , n a m e l y , diffusion, p l a s m o i d s ,
and mul t ipact ing, l i s ted in o rder of decreas ing p r e s s u r e .
The diffusion m e c h a n i s m — s o named because the dominant
mechan i sm of e lec t ron loss is by diffusion to the tube walls and e l ec t rodes—-
occurs throughout a wide range of p l a sma p a r a m e t e r s , i . e . , p r e s s u r e , tube
d imens ions , and applied frequency. Although diffusion has been studied
mainly a s a breakdown m e c h a n i s m , ce r t a in t heo re t i ca l a spec t s of i t s ro le
a s a plasma mechan i sm have a l so been developed and c o r r e l a t e d with e x p e r i
menta l observat ion .
F r o m the standpoint of a p p e a r a n c e , the mos t unusual rf
p l a sma phenomena at low p r e s s u r e s a r e the high-frequency p lasmoids f i r s t 2
repor ted by R. W. Wood in 1930. A high-frequency p lasmoid is a region
R. W. Wood, P h y s . Rev . 35, 673 (1930).
IV-10-1
in a high-frequency p lasma that has a definite sharply bounded f o r m — e . g . ,
a spheroid , spindle , d isk , or pear shape , depending mainly on the p lasma
tube configuration and the pressure—with in which the luminous intensi ty of
the p lasma is usual ly noticeably higher than that of the surrounding p l a s m a .
Although Wood suggested that the p lasmoids were a manifestat ion of an o s
ci l la tory phenomenon, his observat ions did not include any confirmatory 3 4
evidence for this hypothes is . Recent studies at Harwel l , Saclay, and 5
Argonne , however , now tend to confirm Wood's hypothesis and a r e s t a r t
ing to r evea l some of the detai ls of the osc i l la tory m e c h a n i s m .
Multipacting is a l ow-pres su re high-frequency quas i -
osc i l la tory m e c h a n i s m — i . e . , nonharmonic—in which the e lec t ron t rans i t
t ime between e lec t rodes i s nominally
7-cycle and e lec t ron mult ipl icat ion
is by secondary emiss ion due to e l ec
t ron im.pact,on the e lec t rode surfaces ,
with energ ies of the o rde r of 50 ev
or m o r e . Although the mechan i sm
lacks cer ta in impor tant a t t r ibu tes
ord inar i ly a s soc ia ted -with p l a s m a s ,
especial ly a random elec t ron d i s
tr ibution in phase space , it n e v e r
the less has other c h a r a c t e r i s t i c s
that a r e measu rab l e by the same
E . R . H a r r i s o n , J . E lec t ron ics and Control 5 , 319(1958) . (Harwell work . ) "* R. G e l l e r , Compt. rend . 249, 2749(1959). (Saclay work . ) 5 ———
A. J . Hatch, Proceedings of the Four th Internat ional Conference on Ionization Phenomena in Gases ^ , 314 (North-Holland Publishing Company, A m s t e r d a m , I960).
PRESSURE (MICRONS Hg)
Fig . 6. High-frequency p lasma domains in dry a i r . These p l a smas a r e es tabl ished between p lane-pa ra l l e l aluminum elect rodes , 23 cm in d iameter and 15 cm a p a r t , a t a frequency of 15 M c / s e c ,
IV-10-1 21
diagnostic techniques as a r e used in " r e a l " p l a s m a s and the re fore is a u s e
ful neighboring mechan i sm to the p l a smo ids .
The p resen t r e s e a r c h is a imed at studying high-frequency
p lasma and plasmoid phenomena in the gap between the diffusion domain and the
multipacting domain a s shown in F i g . 6. This map of the plasma domains i s
by no means complete; it has been filled in only enough to provide an orienting
reference for the p r e s e n t s tud ie s , and the re a r e s e v e r a l subdomains which
have been recognized but have not yet been explored in sufficient detai l to be
included.
Some idea of the va r i e ty of high-frequency p l a sma phenomena
at low p r e s s u r e s can be gained from examination of the p la sma photos in
F ig , 7. The p l a smas shown in the top th ree photos a r e in the diffusion do
main . Of t h e s e , the only one for which the re is a sa t i s fac tory published 6
theore t ica l descr ip t ion is the doubly s t r i a t ed p l a s m a at 50 jx. The plasma
shown in the 13~jx photo is in the vicinity of the t r ans i t ion at the m e a n - f r e e -
path l imi t , shown in F i g . 6, where the e lec t ron m e a n - f r e e - p a t h i s equal to
the cha rac t e r i s t i c diffusion length. Two s tages in the appea rance of the
high-frequency p lasmoids a r e shown in the photos at 1.0 and 0, 3|x. The
spheroidal dark sheath which del ineates the p lasmoid s e e m s to p re sen t a
paradoxica l situation in that although p lasma boundar ies o rd ina r i ly tend to
beconnie l e s s dis t inct as p r e s s u r e is r educed , th is one beconmes m o r e d is t inc t .
In the 0. 3-ji photo the sheath width i s of the o rde r of 0.002 of the e lec t ron
m e a n - f r e e - p a t h . Dens i tomete r m e a s u r e m e n t s of the negat ive from which
this photo was made show that the luminous intensi ty of the dark sheath
(D = 0.295 a r b i t r a r y units) i s l e s s than that of both the immedia te ly adjacent
W. P . A l l i s , S. C. B rown , and E . E v e r h a r t , P h y s . Rev . 84, 519 (1951).
22 IV- lO- i
HIGH FREQUENCY PLASMAS AND PLASMOIDS
Fig. 7. Photographs of high-frequency p la smas and plasmoids
The p a r a m e t e r s a r e the same as in Fig. 6.
IV- lO- i 23
surrounding p lasma (D = 0. 300) and the plasmoid in t e r io r (D = 0. 340). The
increas ing prominence and d i s t inc tness of the p lasmoids as the abrupt ex
tinction boundary is approached (maintaining voltage in F ig . 6) suggests that
we have h e r e ei ther an isola ted f reakish mechan i sm of no fundamental i m
portance ( there a r e many such in p la sma physics) or a beautiful manifestat ion
of a significant and fundamental p l a sma p rope r ty (there a r e a l so s e v e r a l of
these in p la sma phys ics ) .
The exper imenta l study of the high-frequency p lasmoids in
volves m e a s u r e m e n t s of the axia l va r ia t ion of luminous in tens i ty , dc and
rf potentials in the p l a s m a , and e lec t ron and ion dens i ty , a l l a s functions of
applied rf potent ia l , f requency, e lec t rode separa t ion , and gas p r e s s u r e .
The exper iment i s a clean one in the sense that the p l a smas a r e produced in
the homogeneous e l ec t r i c field between l a r g e - d i a m e t e r p l ane -pa ra l l e l e l e c
t rodes ; t h u s , to the f i rs t approximat ion the osc i l la tory phenomena occur
pa ra l l e l to the ax is and the axia l observa t ions can be c o r r e l a t e d d i rec t ly with
one-dimensional axial theory .
The r e su l t s of the s tudies appear to point toward one p a r a
mount conclusion, namely , that the mode t rans i t ions in F i g . 6 naark the
changeover from osci l la t ions of free e lec t rons in a "nornnal" p la sma to
osci l lat ions of bound e lec t rons in the p lasmoid domain. The equation of
motion of an e lec t ron in a one-d imens iona l p lasma produced by a field
E exp (jwt) i s
x + v x + o j x = (e /m) E exp (j ojt) , (1)
where v is the collision frequency for naomentunn t ransfer (e las t ic m
col l is ions) . The solution of th is equation is
(e /m) E sin 0 ,. . , . X = exp (jwt) , (2)
0) V m
IV-10-1
where
tan e = —^ J . (3) a3p -co
This solution r e p r e s e n t s a forced osci l la t ion. At sufficiently low p r e s s u r e s the
damping t e r m v^^k in Eq. (1) becomes negligible, and the solution above reduces
to
(e /m)E ,. , = -—^ — e x p (j CD t)
OOp^ -OD^ ( 4 )
When 01^^ < 03 the e lec t rons a r e cons idered as free and osc i l la te under the
major influence of the external ly applied driving force . When OD^ > 00 the
e lec t rons a r e cons idered as bound and osc i l la te under the major influence of a
force developed internal ly by charge separa t ion, although the frequency of
osci l lat ion is sti l l controlled by the ex terna l driving fo rce . The binding
force in the plasmoid is due to i ts posit ive dc potential which a r i s e s from
the re la t ively mobile e lec t rons being lost to the tube walls at a higher ra te
(initially) than a r e the re la t ive ly slow ions . As the t rans i t ion f rom free to
bound osci l la t ions occur s , Eq. (4) shows that the phase of the e lec t ron
motion theore t ica l ly undergoes a shift of 180°. Associa ted with this shift
is a phase shift in the self potential of the osci l la t ing e l e c t r o n s . Such a
phase shift has been observed exper imenta l ly in the vicinity of the t r a n s i
tions shown in F i g . 6.
Considerat ions based on this bound e lec t ron m e c h a n i s m
and supported by m e a s u r e m e n t s of the axial profi les of dc and rf potentials
have recent ly led to an explanation of the axial par t of the dark sheath around
the p lasmoids which can be s u m m a r i z e d by r e f e r r ing to F i g . 8. Here a r e
plotted r ep resen ta t ive curves showing the axial profile of the instantaneous
axial rf e l ec t r i c field for the th ree ca ses of no plasma, n o r m a l p lasma, and
the high-frequency plasmoid. In the case of no p lasma the e l ec t r i c field
-10-1
is unifornci. In the no rma l p lasma
the e lec t r ic field has the same
sign al l along the axis even though
i ts magnitude inay v a r y . In
the plasmoid c a s e , however ,
the sign of the e lec t r i c field
inside the plasmoid is opposite
to that outside the plasmoid.
Thus in F ig . 8 the e lec t r ic
field has two ze ros located
approximately at the plasmoid
dark sheath. In the iminediate
vicinity of these two ze ros
there is a smal l zone within
which the rf e lect r ic field i s
l e s s than a "threshold"value
requ i red to cause gaseous
ionization. These two zones
correspond to the axial pa r t
of the plasmoid dark sheath.
UJ
u. o a: o UJ - J UJ u. oc (/) 3 o UJ
< I -
1
^ V ^ V N O R M A L PLASMA / ^ ^
K NO PLASMA-, /7
I • ^ — ^
^ P L A S M O I D x y
^DARK SHEATH^
1
-
- d / 2 + d/2 AXIAL POSITION
Fig . 8. Axial profi les of rf e l ec t r i c field represen ta t ive of the th ree cases indicated. The d a r k -sheath zones in the plasmoid case occur at the field ze ros which r e su l t f rom the phase r e v e r s a l of the field inside the p lasmoid .
The axial dc field has i ts
maximum value just inside the plasmoid sheath and this is where the e l e c
t rons oscillating inside the p lasmoid rece ive thei r tu rn -a round acce le ra t ion .
The sheath can therefore a lso be considered a s the zone within which the
energy of the plasmoid e lec t rons i s below the ionization energy of the g a s .
The osci l la tory motion of the e lec t rons inside the plasmoid is genera l ly
not simple harmonic because mos t of the tu rn-a round acce le ra t ion occurs
only within the na r row sheath. However , a s the conditions of operat ion
in the plasmoid approach the maintaining voltage at low p r e s s u r e and
applied emf as sho-wn in F ig . 6,the ra t io of the sheath width to the p l a s
moid -width i n c r e a s e s and the e lec t ron motion i s bel ieved to become m o r e
IV-10-1
nea r ly ha rmon ic .
Equation (1) is applicable to a wide v a r i t y of high-frequency
p l a sma m e c h a n i s m s . At p r e s s u r e s well above the m e a n - f r e e - p a t h l imit
in F ig . 6, the coll is ion damping t e r m v x becomes impor tan t w h e r e a s the 2
q u a s i - e l a s t i c t e r m w x is negligible and the resul t ing equation e n t e r s into P
the theory of the diffusion m e c h a n i s m . At ve ry low p r e s s u r e s , at which
both V X and cj x a r e negl ig ib le , the resul t ing exp re s s ion x = ( e /m) E exp (jwt)
can be used to desc r ibe e i ther undamped free e lec t ron osc i l l a t ions or the
mult ipact ing m e c h a n i s m by appropr i a t e choice of the boundary condi t ions .
The Tonks -Langmui r type of p l a s m a - e l e c t r o n osci l la t ion a s observed in dc-
excited p l a s m a s can be cons idered as another spec ia l case of Eq . (1) in
which E = 0 and v is negl ig ib le . Here the cohering effect of E exp (jut)
d i s a p p e a r s , thus explaining why the osci l la t ions become difficult to o b s e r v e .
By considering both the p lasmoid osci l la t ions and the Tonks -Langmui r o s
ci l la t ions a s l imiting ca se s of Eq , (1) which r e su l t main ly f rom sheath
effects , and which differ only to the extent of the p r e s e n c e or absence of a
cohering field, one can now see the just if icat ion of Wood's hypothesis that
the two phenomena a r e ve ry c lose ly r e l a t ed .
PLASMAS IN NONHOMOGENEOUS ELECTROMAGNETIC FIELDS
The achievement of control led the rmonuc lea r r eac t ions
r e q u i r e s — a m o n g other th ings—the isola t ion of an e x t r e m e l y hot dense
p l a sma from the naa te r ia l wal ls of a con ta ine r . The s ta t ic or pulsed m a g
net ic fields used for th is pu rpose in mos t expe r imen t s to date have had
the flaw of permi t t ing ins tab i l i t i es to develop with a r i s e t ime of the o r d e r
of a m i c r o s e c o n d . One method of suppress ing the ins tab i l i t i e s i s to r e
v e r s e the containing field in a pe r iod shor te r than the r i s e t ime of the i n
s t a b i l i t i e s , a method which r e q u i r e s the use of h igh-f requency f ie lds .
Seve ra l poss ib le containment methods using the nonhomo
geneous fields in r e sonan t cavi t ies have been p roposed . The pr inc ip le of
such containment has an analogy in the format ion of sand p a t t e r n s along the
IV-10-1 27
nodal lines of 2-dimensional vibrat ing p la tes or m e m b r a n e s — t h e Chladni
sand f igures . P l a s m a s a r e l ikewise expected to be concent ra ted or contained
in the vicinity of the nodal points of the e lec t romagnet ic fields in 3-dimensional
cav i t i es .
One type of containment by cavity f ie lds , which has been
known for seve ra l y e a r s , a r i s e s f rom the Lorentz force exe r t ed on an individual
charged par t ic le in an e lec t romagne t i c field. This force on e lec t rons i s de
r ivable from a sca la r potential
2 l i e / ^ z \ ,^.
4 mw \ / a v '
where — { E ^ is the t i m e - a v e r a g e d square of the e l ec t r i c f ield, / \ '^^ <E " E / . Such $ potential wel ls a r e known to occur in cavity fields of the
e lec t r i c quadrupole type but the i r containment capabi l i t ies a r e l imi ted to low-7
densi ty p l a smas in which oo < w .
The poss ib i l i ty of containing h igh-dens i ty p l a s m a s in the
nonhomogeneous fields of r e sonan t cavi t ies has r ece ived sporad ic at tention
during the past few y e a r s , but none of the proposed containment s chemes has
shown any firm p romise of scientif ic feas ib i l i ty , to say nothing of economic
feasibi l i ty. An analog exper iment was pe r fo rmed about a yea r ago at
Argonne , however , in which the equi l ibr ium p r o p e r t i e s of dense p l a s m a
cores as sinnulated by copper sphero ids were studied in a r e sonan t cavi ty.
F r o m th is exper iment a new and significant r e su l t e m e r g e d , name ly , that
cavity fields of the magnet ic quadrupole t-ype might have the r equ i s i t e
7 The comparat ive values of co and oo a r e a commonly used c r i t e r ion of
re la t ive p lasma densi ty . When o) < co the applied field will pene t ra te the p lasma; when cop > oj the field is apprec iab ly a t tenuated ins ide the p l a sma . ® A. J . Hatch and J . W. B u t l e r , Bul l . A m . P h y s . Soc. 5 , 324 (I960).
IV-10-1
equi l ibr ium and containment p r o p e r t i e s . More r ecen t ly , t heo re t i ca l
s tudies have demons t ra t ed that for v e r y smal l (point) t e s t s p h e r e s of
rad ius r . the magnet ic quadrupole and h igher magnet ic mult ipole modes
in cavi t ies p o s s e s s potent ial wel ls which can be r e p r e s e n t e d by the s ca l a r
point function
T- 2„„ i „ /y\^ - .„ (E=X^ ). (6)
To the extent that such a t e s t sphere can be cons idered a s r e p r e s e n t a t i v e
of a dense p l a s m a , these modes a r e theore t i ca l ly capable of containing
dense p l a s m a s .
Calculat ions of the rf power n e c e s s a r y to contain t h e r m o
nuclear p l a s m a s a t p r e s s u r e s of hundreds of a t m o s p h e r e s in such potent ial
wel ls a r e d i scourag ing . However , p r e s s u r e s of the o r d e r of d y n e s / c m
a r e achievable with re la t ive ly modes t rf power . The effects of such
p r e s s u r e s on p l a s m a s in the m i c r o n p r e s s u r e range should be observab le
provided the i r mani fes ta t ions a r e not o b s c u r e d by competing effects . Thus ,
from the point of view of bas ic p lasma p h y s i c s , the ma in p rob lem i s that
of the in t e rac t ion of p l a s m a s with e l ec t romagne t i c f ields.which now takes
on added i n t e r e s t because of the theore t i ca l ly p red ic ted ex is tence of $
and i h i l l s and wel ls in nonhomogeneous f ie lds . This work i s rece iv ing
continued at tent ion a s a l ikely a r e a for m o r e intensive expe r imen ta l and
theo re t i ca l work in the fu ture .
V-13-1 29
V. THEORETICAL PHYSICS, GENERAL
V-13-1 Spin-Orbit Splitting and Pion Theore t ic L-S Potent ia l (51210-01)
Akito A r i m a , Masao Sugawara , and Tokuo T e r a s a w a '
Concerning the or igin of the sp in-orb i t coupling in nuc le i ,
two of the p resen t authors have recen t ly shown that the s econd-o rde r effect
due to the tensor force i s fair ly l a rge in light nuc le i . The s ame effect has
a l so been shown to give roughly the observed doublet spli t t ings in heavy 2
nucle i . However , the numer i ca l r e s u l t s depend s t rongly on the nuc lea r radi i
a s sumed . If the tensor force suggested by the meson theory i s a s s u m e d
and the nuclear radi i a r e chosen to fit the difference between the Coulomb
energ ies of the m i r r o r nuclei and the e l ec t ron -nuc leus s c a t t e r i n g , the
doublet spli t t ings due to the t enso r force amount to one-fifth to one-half the
observed v a l u e s . If the nuc lear rad i i a r e reduced by 20% or l e s s , the c o r r e s
ponding effect can produce the obse rved v a l u e s . T h e r e f o r e , we have s t r e s s e d
the impor tance of the t enso r force and have concluded that the t e n s o r force 1
explains considerable amounts of the obse rved sp l i t t ings .
Depar tment of Nuclear P h y s i c s , Jajjan Atomic Energy R e s e a r c h Ins t i tu te , T o k a i - m u r a , Iba rak i -ken , Japan ,
1
T. T e r a s a w a , P r o g r , T h e o r e t . P h y s . (Kyoto) 2 3 , 87 (I960); A . A r i m a and T . T e r a s a w a , P r o g r , Theore t , P h y s . (Kyoto) 23 , 115 ( i960); A, A r i m a to be published in Nuclear P h y s . 18. This has a l s o been inves t igated by Wigner and Feingold: E . P . Wigner , Symposium on New R e s e a r c h Techniques in P h y s i c s , Rio de J a n e i r o , 1952; A. M. Fe ingold , P h y s , Rev . 101, 258 (1956). 2
S. Takagi , W. W a t a r i , and M. Yasuno, P r o g r . T h e o r e t , P h y s . (Kyoto) 22, 549 (1959); B . Jancovic i , P r o g r . T h e o r e t . P h y s , (Kyoto) ^ , 585 (1959).
L. Hulthen and M, Sugawara , Handbuch der Phys ik (Edwards B r o t h e r s , Ann A r b o r , 1943) Vol. 39. Concerning the pion theore t i c po ten t i a l s , the works b e fore 1956 a r e s u m m a r i z e d in Suppl, P r o g r . T h e o r e t . P h y s . Ill (1956), edi ted by M. Take tan i .
* B . C. Car l son and I . T a l m i , P h y s . Rev, 96 , 436 (1954).
^ R. Hofs tadter , R e v s , Modern P h y s . 28 , 214 (1956).
v - 1 3 - 1
The purpose of the p r e sen t note i s to r e p o r t that the pion-
theore t i c L - S potential can give other la rge fractions in such a way that the
o v e r - a l l effects just explain the observed spli t t ings without changing nuc lear
r a d i i .
It ha s been known that a strong L-S potent ia l can produce l a rge
doublet spl i t t ings in nuc le i . Severa l au thors have in fact shown recen t ly that
the phenomeno logical L-S potent ial due to G a m m e l and Tha l e r can give l a rge S 9
sp l i t t ings , even values which a r e much g r e a t e r than obse rved . > Here a r i s e s
the quest ion of how la rge the spl i t t ings due to the p ion- theore t i c L-S potential
can b e . This potential i s weaker than tha t of Gamnnel and T h a l e r , but s t i l l
not negligibly s m a l l . In th is note we a s s u m e the L-S potent ia ls tha t were
der ived recen t ly by Okubo and one of the p r e s e n t a u t h o r s , ' We a l so have
re inves t iga ted the G a m m e l - T h a l e r potent ia l a s a check on the prev ious work .
We consider those light nuclei which a r e c losed shel ls plus
or minus one nucleon: He , N , and O . As for the nuc lea r wave functions,
the ha rmon ic osc i l la tor mode l i s a s s u m e d for s impl ic i ty in ca lcu la t ions .
The f i r s t - o r d e r per tu rba t ion exp re s s ions for the doublet spl i t t ings a r e wr i t ten as
6
J . P . El l io t t and A . M. L a n e , P h y s . Rev . 96 , 1160 (1954); R . J . Bl in-Stoyle , P h i l . Mag . 4 6 , 973 (1955); C. A . P e a r s e , P h y s . Rev . 106, 545(1957); B . P . Nigann and M. K. Sundaresan , P h y s . Rev . I l l , 284 (1958). ^ J . G a m m e l and R, T h a l e r , P h y s . Rev . m , 291 (1957); JL_07, 1337 (1957). ® J . Sawicki and R. Fo lk , Nuclear P h y s . j j ^ , 368 (1959); J . Sawicki , Nuclear P h y s . J ^ , 350 (1959).
G. E . Tauber and T - Y . Wu, Nuclear P h y s . 16 , 545 ( I960) . The au thor s a r e v e r y grateful to P r o f e s s o r s T -Y. Wu and G. E . Taube r for informing them of the r e s u l t s of the i r work before publ icat ion.
^° M. Sugawara and S. Okubo, P h y s . Rev . 117, 605 and 611 ( I960) .
Recent ly M. Taketani ajid S. Machida der ived the L-S potent ia l due to the pion t heo ry . The au thor s would l ike to e x p r e s s the i r thanks to P r o f e s s o r S. Machida for his k indness in informing them of the r e s u l t s .
V - 1 3 - i 31
AEp = - I ( 1 P | V _ | l p ) (1)
(2)
and
AE = 4 ( i p I V_ 1 Ip) -I (Zp I V. I 2p) M (U I V_ I If) -f (id I V I Id) , (3)
where E q s . (1) and (3) refer to the c a s e s of one nucleon outside closed shel ls
in the orbi ts Ip and Id , r e spec t i ve ly , and Eq. (2) r e f e r s to the case of 1 5 1 5
N or O . In these equations
oc
( ^ i | V ^ | n ' i ' ) = J R ^ ^ ( r ) R ^ , ^ , ( r ) V ^ ( r ) r ^ d r , (4) r
c
where R (r) is the re la t ive wave function defined in r e f e r e n c e 1 and V, (r) n i ±
a r e the coefficients of the L-S ope ra to r in the two-body nuc lea r potent ial in
the t r ip l e t even and odd s t a t e s , r e spec t i ve ly , L and S being the r e l a t i ve
orbi ta l and total spin angular momen tum o p e r a t o r s of the two-nucleon
sys t em. Since V^ (r) d iverges v e r y badly as r goes to z e r o , and a l s o the
re la t ive wave function R (r) of the two nucleons should van ish inside the n i
h a r d - c o r e r a d i u s , we have a s sumed a ze ro cutoff in Eq . (4) at r equal to
th ree tenths of the Compton wavelength of the pion.
The r e s u l t s a r e sho-wn in F ig , 9 , as functions of the
paranaeter p which i s p ropor t iona l to the nuclear r ad ius and is defined in
re fe rence i . If the wave functions of the pure ha rmon ic osc i l la tor model
a r e a s s u m e d , an exper imenta l value p can be de t e rmined f rom the differ-4
ence between the Coulomb ene rg ies of the m i r r o r nuclei . We have ex
tended calculat ions toward the sma l l e r side of the nuc lea r r ad ius s ince one
v - 1 3 - 1
1.9 2.0 2.1 2.2 /> (IO"'^cm)
2.4
Fig . 9. F i r s t - o r d e r doublet splittiiig AE for He^ and L i ^ , N^^ and O , and O"*- and F ^, aga ins t p which is propor t ional to the nuclear r a d i us and defined as (2 /v)2 and v = ma)/-ii, m being the nucleon m a s s and u) the angular frequency of a harmonic osc i l l a to r . Ver t ica l l ines indicate the value of p that i s de termined from the difference between the Coulomb energies of the m i r r o r nuc le i . The G-T curves refer to the Gannmel-Thaler potential ( reference 7) and ps and pv curves a r e the effects of the pion theore t i ca l potent ials ( r e ference 10) with p s - p s and ps-pv couplings, r espec t ive ly . Dotted lines a r e second-orde r effects due to the pion theore t ica l tensor force and have been taJcen from reference 1 Exper imenta l values a r e indicated by horizontal l ines (or a shaded band).
can argue that taking p < p m a y
be reasonable because of the a d
mix tu re of higher s ta tes due to
h i g h e r - o r d e r per turba t ions and
the sho r t - r ange cor re la t ion .
It is v e r y i n t e r
esting that the L-S potential sug
gested by the pion theory can
produce the la rge doublet sp l i t t ings ,
especia l ly in the ps -pv c a s e . Even
in the p s - p s c a s e , the contribution
has the same o rde r of magnitude
a s that due to the tensor fo rce .
T h e G a m m e l - T h a l e r L-S potential
s e e m s to give split t ings that a r e
somewhat too l a rge . The even-
state L-S in teract ion is cons ide r
ably l e s s impor tant in producing
doublet spli t t ings than the odd-s ta te
in te rac t ion . There fo re , a s far a s
the odd-s ta te L-S potential is
a t t r a c t i v e , the sign of the splitting
is c o r r e c t , and this is the case in
a l l potentials assunmed. ' B e
cause of the shor t - range na ture
of the L-S potent ia ls , one might
think that our zero cut-off procedure
in Eq . (4) might lead to a se r ious
overes t imate compared -with the
case in which a proper corre la t ion
-1 33
function is introduced into the wave function R (r) in Eq . (4). We have , n i
g
t he re fo re , compared our r e su l t with that of Tauber and Wu, who used the
G-T potential and introduced the cor re la t ion function. Our r e su l t is only
about 10% la rge r than the i r r e s u l t in N at the same p. There fore our r e s u l t
cannot be too much of an o v e r e s t i m a t e . We have a l so e s t ima ted the magnitude
of the second-order effect. The effect can be calcula ted in the same way as
is outlined in the previous p a p e r s . A nucleon inside the closed shel l i n t e r
ac t s -with the outside nucleon and both can jump into higher Orbits . The
second*order cor rec t ion to the doublet splitting is finally given by
< ' = - | S s d r ('p|v l N . i p ) Y i - ^ j ,
where co is the angular frequency of a ha rmonic osc i l l a to r . The co r r ec t ion 12)
AE is es t imated only for the G-T potent ial and at p = 2 . 4 . It has the
opposite sign to AE given by Eq . (1) and is about 25% of AE , or l e s s . P P
We may hope that the higher o rde r co r r ec t ions would not affect our r e s u l t s
d ras t i ca l ly .
As the conclusion, the doublet spl i t t ings a r e adequately
explained in a l l th ree nuclei cons ide red in t e r m s of the combinat ion of the
s econd-o rde r effect due to the t ensor force and the f i r s t - o r d e r effect due to 3 I D
the L-S potent ial , both of which a r e suggested by the p r e sen t pion t h e o r y ,
if the ps-pv coupling is a s s u m e d and a l so the nuc lear r ad ius i s chosen at p .
The spli t t ings obtained from the p s - p s theory s e e m to be somewhat s m a l l ,
while those from the G a m m e l - T h a l e r potential s e e m too la rge for the s ame
p. However , the sma l l e r p may be m o r e r e a s o n a b l e , a s we have d i scussed
be fo re . T h u s , it i s cer ta in ly p r e m a t u r e to ru le out the p s - p s case on this
b a s i s a lone . We a lso r e c a l l that the der iva t ion of the L-S potent ial in the
p s - p s coupling contains ce r t a in ambigu i t i e s . T h e r e f o r e , we cer ta in ly cannot
d i sc r imina te the p s - p s and p s - p v couplings. Our posi t ive s ta tement is that
the she l l -model doublet spl i t t ings do not indicate any u rgen t need for introducing
v-13 -1 V - 4 2 -
phenomenological L-S potent ials bes ides those a l r eady expected from the
pion theory .
V-42-1 Geome t r i c Theory of Charge (51151-01)
H. Eks te in
The "explanat ion" of e l ec t r i c i ty has been an age-o ld
d r e a m of p h y s i c i s t s . Students of the h i s to ry of phys ics know about one-
fluid and two-fluid t heo r i e s of e lec t r i c i ty and about mechan ica l e ther
t h e o r i e s . The path of phys ics i s s t rewn -with skele tons of such t h e o r i e s .
After many f a i l u r e s , phys ic i s t s have r e s igned t h e m s e l v e s to consider e l e c
t r i c i ty a s a phenomenon of i t s o-wn, not reduc ib le to off- explainable in t e r m s
of other phenomena. But , a s cocks cannot stop crowing, so phys ic i s t s
cannot stop trying to simplify the p ic tu re of n a t u r e , i , e , , to d e c r e a s e the
number of sepa ra t e a s sumpt ions needed.
The p r e sen t paper t r i e s to deduce the m o r e b a s i c a spec t s
of e lec t r i c i ty from such p r i m e pr inc ip les a s r e l a t i v i s t i c covar iance and
pr inc ip les of quantum m e c h a n i c s . What a r e these ba s i c a s p e c t s ? F i r s t ,
the exis tence of two dis t inc t t-ypes of p a r t i c l e s , such a s e lec t rons and p o s i
t r o n s , tha t have ident ica l mechan ica l p r o p e r t i e s . Second, the exis tence
of a conserved quantity (the charge) which would be jus t the difference
between the n u m b e r s of posi t ive and negative p a r t i c l e s if t h e r e were only
e lec t rons and pos i t rons in the wor ld , but which h a s a m o r e subtle meaning
in the p r e s e n c e of other p a r t i c l e s such a s p ro tons and an t ip ro tons . T h i r d ,
the curious fact tha t the charge never changes a s the r e s u l t of any m e a s u r e
men t . This is m o r e than a conservat ion p r o p e r t y , for the energy (which is
conserved) may well be changed by an ex te rna l measu r ing s y s t e m . Th i s
42-1 35
"superconse rva t ion" p roper ty of e l ec t r i c charge is exp res sed by a " s u p e r -
select ion r u l e . "
The main assumpt ion is covar iance of na tu ra l laws under
the full Lorentz group^ including space and t ime r e v e r s a l . This a s sumpt ion ,
together with some of the bas ic pr inc ip les of quantum m e c h a n i c s , i s s u r p r i s i n g
ly powerful for the ana lys i s of one-par t i c le s y s t e m s , in that it r e s t r i c t s the
number of poss ib i l i t i e s . One of the oldest examples of this power is the
p red ic t ion that spins can be only in tegra l or ha l f - in tegra l—not of any i n t e r
media te va lue . The type of s ta tements in a theory of this kind ("Wigner ism"
for short) i s not mainly "if A , then B , " a s in dynamical t heo r i e s ( e . g . ,
Newton's equat ions) . It is r a t h e r : "A or B may ex i s t , but not C" ( e . g . ,
the spins may exist only with the va lues mentioned above). This can be
provided by p r inc ip les that r e s t r i c t the number of a p r i o r i poss ib i l i t i e s . The
purpose of the game isunot jus t to postulate a scheme that is consis tent with
e x p e r i m e n t , for the s imples t such s ta tement would be: "Anything may e x i s t . "
The s u c c e s s of such a theory is m e a s u r e d by the number of conceivable
objects forbidden by theory provided tha t , in fact , they a r e not obse rved .
This should be a c t o m p l i s h e d by use Of the sma l l e s t poss ib le number of
p r inc ip les or a s s u m p t i o n s . A figure of m e r i t of the theory might be
number of excluded poss ib i l i t i es number of a s sumpt ions (or pr inc ip les )
A l e s s quanti tat ive c r i t e r ion used by judges in theory-beau ty contes ts is
the " s impl i c i ty" or "e legance" or "plausibi l i ty" of the p r i n c i p l e s . It i s
indispensable to make such a r e q u i r e m e n t , because it is technical ly always
possible to s u m m a r i z e any number of s t a tements by the symbolic equation
X = 0.
The set of p r inc ip les which we use can c la im plausibi l i ty
because each of them i s (almost) s epa ra t e ly and d i rec t ly ve r i f i ab le , i . e . ,
the observab le impl ica t ions of the p r inc ip les can be t e s t ed m o r e or l e s s
V-42-1
d i rec t ly . This i s v e r y different from a quantum field theory , for which the
set of a l l a ssumpt ions may (or may not , we do not know) lead by a compl i
cated ma themat i ca l p rocedure to predic t ions comparable and consistent with
exper imen t .
F u r t h e r m o r e , a g rea t effort is made to accept only the
m o s t gene ra l assumpt ions that imply observed r e s u l t s . A good example of
th is effort i s the h is tory of the ma thema t i ca l formulat ion of s y m m e t r y in
Hi lber t space . It was or iginal ly a s s u m e d that ope ra to r s mus t form a r e
presenta t ion of the s y m m e t r y g roup . This assumpt ion indeed impl ies the
observed s y m m e t r i e s of observable quan t i t i e s , but it i s not the m o s t gene ra l
assumpt ion that accompl i shes this p u r p o s e . T h e r e f o r e , the assumpt ion was
modified to loosen the connection demanded between group and o p e r a t o r s .
The cu r r en t ly accepted r e q u i r e m e n t is that the o p e r a t o r s m u s t form a co-
r e p r e s e n t a t i o n , up to a factor of modulus uni ty , of the s y m m e t r y g roup .
This means (1) that instead of mimicking the group^multiplication table
^ 1 ^ 2 - ^ 1 2
(la)
U(L^) U d . ^ ) = U(L^2)
the o p e r a t o r s U (L) m u s t only satisfy an a lgebra
U ( L , ) U ( L 3 ) = e ^ * < ^ V ' ^ ' - U ( L 3 . 2 ) V (lb)
(2) that the o p e r a t o r s do not have to be un i ta ry but that some of them may
be an t iun i ta ry . That i s , ins tead of having the l inear p rope r ty
U(af + bg ) = a U f + b U g
(where a , b a r e numbers and f, g a r e v e c t o r s in Hi lber t space) , the opera
t o r s m a y have the ant i l inear p rope r ty
V - 4 2 - i "
U(af + bg)= a Uf + b Ug .
This less r e s t r i c t i v e ma themat i ca l r e q u i r e m e n t a l so impl ies the observed
s y m m e t r y p rope r t i e s but , being less r e s t r i c t i v e , al lows for m o r e poss ib i l i
t i e s , some of which we know to be r ea l i zed . The cur ren t ly accepted fornaalism
may st i l l be too r e s t r i c t i v e . At any r a t e , one of the main preoccupat ions of
Wigner i s t s (or Wigner ianers ?)is the avoidance of r e s t r i c t i o n s imposed for
ma themat i ca l convenience r a t h e r than by physical p r i nc ip l e s .
One of the main assumpt ions is that one-par t i c l e s ta tes a r e 1
to be d e s c r i b e d b y i r r e d u c i b l e r e p r e s e n t a t i o n s of the L o r e n t z g r o u p . T h e
j u s t i f i c a t i o n for t h i s a s s u m p t i o n i s a s f o l l o w s . It can b e shown (a) t h a t the
o p e r a t o r P P ( w h e r e the P a r e t h e g e n e r a t o r s of t h e s p a c e - t i m e t r a n s -|x p. Il
l a t i o n s ) c o m m u t e s wi th a l l g r o u p o p e r a t o r s , and (b) t ha t in i r r e d u c i b l e r e
p r e s e n t a t i o n s ( S c h u r ' s Lemma) s u c h a n o p e r a t o r i s a c o n s t a n t , i . e . ,
P P = - m .
I t fo l lows t h a t t he t i m e - t r a n s l a t i o n o p e r a t o r P c a n , in an i r r e d u c i b l e r e
p r e s e n t a t i o n , b e e x p r e s s e d a s a funct ion of t h e s p a c e - t r a n s l a t i o n o p e r a t o r s
^k = 2 i
^0 = (^k^k ^ - ) 2
In this c a s e , the t i m e - t r a n s l a t i o n is the re fore a function of space - t r ans l a t i ons ,
and the re fore any s ta te
1
A ternminological note: (1) While , as mentioned above , we a r e now looking for co rep resen ta t ions up to a factor r a t h e r than for r e p r e s e n t a t i o n s , we will s t i l l use the shor t word " r e p r e s e n t a t i o n . " To avoid ambigui ty , we may refer to " p r o p e r r ep re sen ta t ion" when we rea l ly mean r ep re sen t a t i on . (2) F r e n c h phys ic i s t s have long r e f e r r e d to the Loren tz group as the Po incare g roup . Fo r N A T O a m i t y a s well a s for h i s to r i c j u s t i c e , we should accept this change of n a m e , for Loren tz had rea l ly nothing to do with the g roup . The c red i t may be split between Po inca re and E ins t e in , but so many things bea r E ins t e in ' s name that it i s only fair to a t t r ibute the group to P o i n c a r e .
V - 4 2 - i
- ^ 0 ^
^
which develops in t ime t from an ini t ia l s tate \\i may be obtained a l so by
an appropr ia te l inear combination of space - t r ans l a t ed vec to r s
e ijj
Stated crudely: an ini t ial s ta te de sc r ibed by an i r r educ ib le r ep resen ta t ion
does not "essen t i a l ly" change during t ime-deve lopmen t , because the la ter
s t a tes a r e just l inear combinations of the space- t rans labes of the ini t iaT
s t a t e . This i s (almost) an experimiental tes t of i r r educ ib i l i ty .
Stable one -pa r t i c l e s ta tes mee t th is specification; two-
par t i c l e s ta tes do not , because—for i n s t a n c e — n o space - t r ans l a t i on of an
e l ec t ron -pos i t ron sys tem will produce gamma r a y s . A l so , unstable
p a r t i c l e s do not r ea l ly m e e t the r e q u i r e m e n t , because (as another example)
no space - t r ans l a t i on of a TT will produce gamma r a y s . N e v e r t h e l e s s ,
it i s u sua l to consider unstable pa r t i c l e s a s being approximate ly desc r ibed
by i r r educ ib le r e p r e s e n t a t i o n s . T h u s , the p r i m a r y subjects of s y m m e t r y
theory a r e the s imples t s y s t e m s (one-par t i c le s ta tes) that a r e de sc r ibed
by i r r educ ib l e r e p r e s e n t a t i o n s . One should expect that the enumera t ion
of the i r r educ ib l e r e p r e s e n t a t i o n s of the Po inca re group will p red ic t the
g e n e r a l p r o p e r t i e s of a l l p a r t i c l e s .
To what extent has th is expectat ion been r ea l i z ed? One
of the str iking facts about e l emen ta ry p a r t i c l e s is that they often occur in
doub le t s—elec t rons and p o s i t r o n s , posi t ive and negative p ions , e t c .
Until r e c e n t l y , the only i r r educ ib l e r e p r e s e n t a t i o n s known a t t r ibuted only
one l inear ly independent s ta te to a sp in less pa r t i c l e with given m a s s and
m o m e n t u m , two to a spin-|^ p a r t i c l e , and , m o r e gene ra l l y , 2s + 1 l inear ly
independent s ta tes to a par t i c le with spin s. If this were t r u e , the in
t roduct ion of e l ec t r i c charge a s a s epa ra t e and super imposed entity would
v - 4 2 - 1 39
indeed be indispensable—or e lse how can the exis tence of two mechanica l ly
equal copies for the e lect ron be explained?
Of c o u r s e , pure s-ymmetry theory does not exclude the
possibi l i ty of two i r reduc ib le r ep resen ta t ions with exactly equal m a s s and spin ,
but this would be an acc ident . If we wish to obtain nontri-vial r e s t r i c t i o n s from
s-ymmetry t heo ry , we mus t adopt the pr inc ip le : acc idents don' t happen.
For tuna te ly , the complete theory of s y m m e t r y is r i c h e r ,
and it does provide for the possibi l i ty of two such s t a tes ; in technical language,
there exist i r reduc ib le r ep resen ta t ions in which the re a r e two l inear ly inde
pendent vec to r s with given m o m e n t u m , mass^and spin project ion on the m o m
entum. T h u s , we can explain the exis tence of posi t ive and negat ive pa r t i c l e s
with equal mechan ica l p r o p e r t i e s .
What i s m o r e impor tan t i s that the re a r e only two such
l inear ly independent s ta tes poss ib le in an i r r educ ib le r e p r e s e n t a t i o n . This
(on the assumpt ion that we a r e just if ied in equating the charge doublets to the
doublets predic ted by the theory) p r ed i c t s that the re can be only double ts ,
and not t r i p l e t s , quadrup le t s , e t c . This predic t ion is indeed in ag reemen t
with exper imen t , although approx imate mul t ip le ts of higher o r d e r ex i s t ,
e . g . , the neu t ra l pion in addition to the two charged ones—but i t s m a s s is
not quite the same .
It is encouraging that pure ly geome t r i c cons idera t ions
explain the dual ( ra ther than t r ip le or sextuple) na ture of e l ec t r i c i t y . How
e v e r , the "doubled" r ep re sen ta t ions of the theory a r e too n u m e r o u s ; they
allow for too many poss ib i l i t i e s .
Another phys ica l pr inc ip le will be needed to obtain non-
t r iv ia l r e s u l t s . After the painful exper ience of pa r i t y -nonconse rva t ion , mos t
phys ic is t s will ag r ee that invar iance p r inc ip les should be t e s t ed exper imenta l ly
before they a r e r a i s e d to the dignity of fundamental pos tu l a t e s . But , before
being ver i f ied ,a pr inciple mus t be e x p r e s s e d in an exper imenta l ly ver i f iable
way. The pr incip le of t i m e - r e v e r s a l i n v a r i a n c e , a s o rd ina r i ly s t a ted , does
v - 4 2 - 1
not satisfy this r e q u i r e m e n t , and an addit ional or m o r e complete formulation
is needed.
To see how t i m e - r e v e r s a l differs from other i n v a r i a n c e s ,
let us r e s t a t e c lea r ly what i s mean t by invar iance or s y m m e t r y of na tu ra l
l aws . This s ta tement will avoid the use of coord ina tes . These a r e somet imes
useful , but always a r b i t r a r y , conventions and thei r introduction at this point
tends to obscure the s imple in t r in s i c meaning of the s t a t e m e n t s .
Given a s ta te ^ specified by a complete set of m e a s u r e
men t s at one t ime (say, t = 0) , t h e r e ex i s t s an image state ig =. U (L)TE
induced by an invar iance e lement L. In our s c h e m e , L includes the set of al l
l eng th -p rese rv ing mappings of s p a c e - t i m e into i tself . The s ta te U (L)^ is
obtained from •$ by making a ce r t a in t-ype of change in the equipment which
produced •$, th is change being de te rmined by L a s follows. If L is a
t r a n s l a t i o n , the equipment i s to be t r a n s f e r r e d to another point -without
ro ta t ion . If L i s a space - ro t a t i on , the equipment i s to be ro t a t ed -with r e
spect to i t s fo rmer posi t ion. If L i s a " p r o p e r " Lorentz t r a n s f o r m a t i o n ,
the producing equipment i s to be put on a moving suppor t . The predic t ion
of the invar iance pr inciple is then that a l l m e a s u r e m e n t s made a t a l l t imes
on ^ will be r e l a t ed to those made on ^ in the s imple -way impl ied by the
g e o m e t r i c meaning of L, Fo r i n s t ance , the obse rved va lues on U(Tr)TS
(Tr being a space t rans la t ion) will be numer i ca l ly equal at points T r P to
those made a t points P in the or ig ina l exper iments on ^, The impl icat ion
of other invar iance operat ions will be sufficiently c lea r by analogy to t h i s .
The one except ion to th i s opera t ional i n t e rp re t a t i on of
invar iance is t i m e - r e v e r s a l . What i s the ins t ruc t ion for the p r epa ra t i on
of a s ta te U ( T ) T E ? One occas ional ly finds textbook s ta tements about "let t ing
t ime run backward" but th is i s c l ea r ly a m a n n e r of speaking and not an
opera t iona l in s t ruc t ion .
Consider f i r s t the c l a s s i ca l c a s e . The s t a t emen t i s :
given that a c l a s s i ca l s ta te ^ . (specified by pos i t i ons , m o m e n t a , and possibly
in t r in s i c angular momenta of a l l p a r t i c l e s at one t ime) evolves into a s tate
v - 4 2 - 1 41
"ij. after a t ime t , then there ex is t s a s tate T-^. which evolves into a s ta te f f
T^. during t ime t . The s ta tement i s empty un less an ins t ruc t ion for the p r e
para t ion of any state T ^ corresponding to a given ^ is provided. The s t a t e
ment would be empty if this ins t ruc t ion had to re ly on a specific t h e o r y , since
symmet ry s ta tements should be imposed on a theory , and not be deduced from
i t . In fact, the ins t ruct ion is easy to formulate : T ^ is obtained from <k by
revers ing a l l momenta and angular momenta and leaving the posi t ions unchanged.
In th is pure ly emp i r i c a l f o r m , the s ta tement is ve r i f i ab le ,
and has been verif ied to a la rge extent . The essen t ia l point i s that a d i rec t ly
verif iable s ta tement of t i m e - r e v e r s a l invar iance has to be made in t e r m s of
a geomet r i c operat ion (180° ro ta t ion) .
For at leas t a r e s t r i c t e d set of ( improper) quantum
mechanica l s t a t e s , the c l a s s i ca l s t a tement can be immedia te ly adapted: F o r
a one-par t i c le s tate which is a s imul taneous eigenvector of momen tum p and
of the project ion s of the angular momen tum (s = J -p , / p ) on i t , the t i m e -
r e v e r s a l opera tor is equivalent to a 180 rota t ion -with r e s p e c t to a d i rec t ion
no rma l to p , i . e . ,
U(T)ife = e ' '^U(R ) if (2) p , s p p , s
- p , s .
In this form the s ta tement is in a g r e e m e n t with observa t ions a s well a s
with al l t heor i e s of e l emen ta ry p a r t i c l e s cons idered in the p a s t . In the case
of the "doubled" r e p r e s e n t a t i o n s , however , not a l l s imul taneous e igenvec
t o r s of p and s satisfy Eq, (2) and the re fo re we have to impose it a s a c o n
dition on s t a t e s .
The fact that some v e c t o r s in Hi lber t space do not r e
p r e s e n t physical ly rea l i zab le s t a t e s i s not new but s t i l l unfamil iar to m o s t
phys i c i s t s . In conventional quantum m e c h a n i c s a s formula ted by D i r a c or
v - 4 2 - 1
von Neumann, the re was a one- to-one assoc ia t ion between the r a y s of Hi l -i6
be r t space ( i . e . , the vec to r s mul t ip l ied by any phase e , s ince phases
a r e not observable) and observable "pu re s t a t e s . " This i s p a r t of the
conventional set of a x i o m s .
However, this axiom cannot be c o r r e c t . It i s known that
a ro ta t ion through 360 produces a vec tor - ^ for a spin-j^ s y s t e m , but a
vector +^ for a sp in less sys tem such a s the vacuum. By i tself , th is i s not
dis turbing since phase fac tors ±1 a r e not observab le . But if we cons ider
a vec tor ^ + it. ,^ , a l inear combination between the vacuum state and a
state of spin j , then a rotat ion through 360° produces ^ - • $ . . - , , which
is not equal to the or iginal vec tor even up to a factor of unit modu lus . Yet,
a rotat ion through 360 cannot poss ib ly change the physica l na tu re of a
system.4 We mus t conclude tha t , although ^ +•>$:. ,^ i s a wel l -def ined
vector in Hi lber t s p a c e , it does not c o r r e s p o n d to a r ea l i zab le s t a t e . This
does not exclude the exis tence of a sy s t em that somet imes gives the resu l t
0, and at o ther t i m e s the r e s u l t j for the obse rved value of the angular
m o m e n t u m . Such a sys tem might be de s c r i be d by a s t a t i s t i ca l ( incoherent)
mix tu re of spin-0 and spin~-|- s t a t e s . Con t r a ry to conventional quantum
m e c h a n i c s , the Hi lber t space of phys ics has holes in which v e c t o r s languish
without the dignity of s t a t e s .
Our p r i nc ip l e , which r e q u i r e s an exper innental ver i f iabi l i ty
of t i m e - r e v e r s a l s y m m e t r y , r e l e g a t e s many vec to r s to th is pu rga to ry of
n o n - s t a t e s . In p a r t i c u l a r , a l l but one of the "doubled" r e p r e s e n t a t i o n s tu rn
out to have no s ta tes a t a l l , and can be d i s c a r d e d . This i s the d e s i r e d r e
sult of a phys ica l pr inciple in a s y m m e t r y theory : it r e s t r i c t s the number
of p o s s i b i l i t i e s .
The remain ing "doubled" i r r educ ib l e r e p r e s e n t a t i o n has
some s t a t e s , but mos t of i t i s in p u r g a t o r y . In technica l language , t h e r e
i s a super se lec t ion ru le within the i r r e duc ib l e r e p r e s e n t a t i o n . Two sub-
s p a c e s , each of which i s i r r educ ib l e under the r e s t r i c t e d P o i n c a r e g r o u p .
v - 4 2 - 1 43
a r e separa ted by super se lec t ion, i . e , , l inear combinations of v e c t o r s from
the two subsp)aces a r e not s t a t e s . Obviously, we identify the v e c t o r s in
the two subspaces with posit ive and negative p a r t i c l e s , r e spec t ive ly , and
we have—from genera l pr inc ip les only—deduced or "p red ic ted" the supe r -
select ion which is consistent with obse rva t i ons .
The superse lec t ion ru le can be extended deductively to
many-body s t a t e s . It then s ta tes that sys t ems having different values of
the difference between the number of posi t ive and of negative p a r t i c l e s ( i . e . ,
sys tems for which n - n ?£ n - n ) a r e sepa ra ted by supe r se l ec t ion .
One obtains a l so the " supe rconse rva t ion" of a quantity Q (charge) which is
p ropor t iona l to the difference between the number s of posi t ive and negative
p a r t i c l e s .
The two one -pa r t i c l e subspaces a r e connected by the
opera tor that r e p r e s e n t s space i nve r s ion , i . e . , the m i r r o r image of a
posi t ive pa r t i c l e is a negative p a r t i c l e , and the m i r r o r image of a neut ron
is an an t ineut ron . One should expec t , on the b a s i s of this s y m m e t r y
p rope r ty , that in some exper imen t s the posi t ive par t i c le will r e v e a l i t s lack
of m i r r o r s y m m e t r y .
In one sense then, the pure s y m m e t r y theory p red ic t s
the Wu exper imen t . I t i s i ron ic to ref lec t that if these cons idera t ions on
the bas i s of a s s u m e d full r e l a t i v i s t i c s y m m e t r y had been c a r r i e d out in
1940—and the re is no r e a s o n why this could not have been done—physic is t s
would have expected r e s u l t s of the "pa r i ty -nonconse rva t ion" t-ype just b e
cause of invers ion symimetry of n a t u r a l l a w s .
Work on th is p ro jec t has been completed and the r e s u l t s
have been published in a r e p o r t ent i t led: " G e o m e t r i c Theory of C h a r g e , "
H. Eks t e in , P h y s . Rev . 120, 1917 = 1924 (December 1, I960) .
m
PUBLICATIONS SINCE THE LAST REPORT
PAPERS
MEASUREMENTS OF SPATIAL ASYMMETRIES IN THE DECAY OF POLARIZED NEUTRONS
M. T . Burgy , V. E . Krohn , T. B . Novey, G. R.. Ringo, and V. L. Telegdi . (Pro jec t 1-123)
P h y s . Rev . 120, 1829-1838 (December 1, I960) .
GEOMETRIC THEORY O F CHARGE
P h y s . Rev . | ^ , 1917-1925 (December 1, 1960).
NUCLEAR DEFORMATION IN THE SPHEROIDAL SHELL MODEL
Kiuck Lee and D. R. Ing l i s , , . . . . . . . . , . . . , , . , , (Pro jec t V-3) Phys , Rev , jL20, 1298-1302 (November 15, I960) .
LIVING AND WORKING AT HARWELL
Alexander Langsdorf , J r . Phys ics Today 13 (11), 16-19 (November I960) .
NUCLEAR SPIN AND HFS OF Ge^^
W. J . Childs and L . S. Goodman. , , . . (P ro jec t 1-80) Bul l . A m . P h y s . Soc, 5 , 411 (November 25 , I960),
LEFT-RIGHT ASYMMETRY IN THE SCATTERING OF POLARIZED NEUTRONS FROM LIGHT NUCLEI
A . J . Elwyn and R. O. Lane , . . . , , . . . . . ( P r o j e c t 1-18) Bul l . A m . P h y s . Soc, 5, 410 (November 25, I960) .
MOSSBAUER E F F E C T IN FERROMAGNETIC ALLOYS O F Sn^^^ II
S. S. Hanna, L , M e y e r - S c h u t z m e i s t e r , R. S. P r e s t o n , and
Bul l . A m . Phys , Soc, 5 , 429 (November 25 , I960) .
DECAY OF Tm^"^^
R. G. Helmer and S. B . B u r s o n . (Pro jec t 1-33) Bu l l . A m . P h y s . Soc. _5, 425 (November 25 , i960) .
6 l T 3 T9 R 5 1 2 3 LIFETIMES OF EXCITED STATES O F Ni , Ga , B r , Rb , AND Sb
R. E . Holland, F . J . Lynch, and E . N. Sh ip ley . . (P ro jec t 1-14) Bul l . A m . P h y s . Soc. 5 , 424 (November 25 , i960) .
45
ISOTOPIC IDENTIFICATION OF NEUTRON RESONANCES IN Cd FROM CAPTURE GAMMA-RAY SPECTRA
H. E . Jackson and L. M. Bol l inger . . „ . , (Projec t 1-3) Bul l . A m . Phys . Soc ._5 , 409 (November 25 , I960) .
ANALYSIS OF THE STRUCTURE OF NUCLEI FROM (d,t) REACTIONS
B . J . R a z , B . Ze ldman , and J . L, Y n t e m a . . . . . . (Pro jec t 1-22) Phys . Rev. 120, 1730-1737 (December 1, I960).
REPULSION OF ENERGY LEVELS IN COMPLEX ATOMIC SPECTRA
Norbe r t Rosenzweig and Char l e s E . P o r t e r . . . . . . (Pro jec t V-15) P h y s . Rev . _1_20, 1698-1714 (December 1, 1961).
SYSTEMATIC ERRORS IN THE DIRECT MEASUREMENT O F NUCLEAR LIFETIMES IN THE SUB-MILLIMICROSECOND REGION
E . N. Shipley, F . J . Lynch, and R. E . H o l l a n d . . . (Pro jec t I-14) Bul l . A m , Phys , Soc. _5, 424 (November 25, I960) .
CAPTURE GAMMA RAYS FROM Cd^^^(n,v) Cd^^*
R. K. Smither (Pro jec t 1-60) Bul l . A m , P h y s . S o c . J , 409 (November 25 , I960) .
SIMPLIFICATION OF CARATHEODORY'S TREATMENT O F THERMODYNAMICS
Louis A. Turner A m . J . P h y s . 28, 781-786 (December I960) .
5 7 TEMPERATURE DEPENDENCE OF THE MOSSBAUER SPECTRUM IN Fe
D. H. Vincent , R. S, P r e s t o n , J . H e b e r l e , and S. Hanna (Pro jec t I-19) Bul l . Am, P h y s . Soc. 5_, 428 (November 25 , I960) .
ENERGY DEGRADING-FOCUSING OF CYCLOTRON BEAM
W. J . R a m l e r , J . L„ Yntema , and M. Oselka . . . (P ro jec t 1-22) Nuclear I n s t r . and Methods 8, 217-220 (I960).
(d,t) REACTIONS ON NUCLEI WITH A « 60
B . Ze ldman , J . L . Yntema, a n d B . J . R a z . . . . . . . . . (Pro jec t 1-22) P h y s . Rev. 120, 1723-1730 (December 1, i960) .
ADDITIONAL PAPERS ACCEPTED FOR PUBLICATION
DECAY OF sgEr^®^ (3. 1 hr)
H. A . Grench and S. B . Bur son (Projec t 1-30) P h y s . Rev. in F e b r u a r y 1, 1961 i s s u e .
E F F E C T OF RADIOFREQUENCY RESONANCE ON THE NATURAL LINE FORM
M. N. Hack and M, H a m e r m e s h . , (Pro jec t 1-19) Nuovo c imento .
PROPOSAL FOR DETECTING THE POLARIZATION O F SLOWPROTONS
Juergen Heber le Helv. P h y s . Acta (Internat ional Symposium on Po la r i za t ion Phenomena of Nucleons) in December I960 i s s u e .
THE ANGULAR DISTRIBUTIONS OF NEUTRONS SCATTERED FROM VARIOUS NUCLEI
R. O. Lane , A . Langsdorf, J r . , J . E . Monahan, and A . J . Elwyn (Pro jec t 1-18)
Ann. P h y s . in F e b r u a r y 1961 i$suQ,
PRINCIPLES O F CYCLIC PARTICLE ACCELERATORS
John J . Livingood. D. VanNostrand about June 1961,
THE CRYSTAL STRUCTURE O F LITHIUM TUNGSTATE
W. H. Zacha r i a sen and H. A. P le t t inger (Pro jec t III-10) Acta C rys t . (about January 1961 i s s u e ) .
THE CRYSTAL STRUCTURE OF GADOLINIUM TRICHLORIDE HEXAHYDRATE
M a s s i m o M a r e z i o , H. A. P l e t t i n g e r , and W. H. Z a c h a r i a s e n Acta Cryst*(about January 1961 i s s u e ) .
P E R S O N N E L CHANGES IN T H E A N L PHYSICS DIVISION
D E P A R T U R E S
D r . Ak i to A r i m a jo ined the P h y s i c s D i v i s i o n a s a R e s i d e n t R e s e a r c h
A s s o c i a t e on S e p t e m b e r 14 , 1959 . He h a s b e e n i n t e r e s t e d in
s p i n - o r b i t sp l i t t i ng a n d t e n s o r f o r c e , s p i n - o r b i t s p l i t t i n g and
p ion t h e o r e t i c L - S p o t e n t i a l , a n d the i n f l u e n c e of s h o r t - r a n g e
t w o - b o d y i n t e r a c t i o n s on t h e e q u i l i b r i u m d e f o r m a t i o n of nuc le i
( P r o j e c t V - 1 3 ) . He t e r m i n a t e d a t A N L on D e c e m b e r 7 , I960
t o r e t u r n to the I n s t i t u t e for N u c l e a r S t u d y , U n i v e r s i t y of
T o k y o , T o k y o , J a p a n .
D r s . H e r m a n A . T a s m a n j o i n e d the P h y s i c s D i v i s i o n a s a R e s i d e n t R e
s e a r c h A s s o c i a t e on M a y 3 1 , I 9 6 0 . He h a s c o l l a b o r a t e d wi th
W. A . Chupka a n d J . B e r k o w i t z on h i g h - t e m p e r a t u r e t h e r m o
d y n a m i c s t u d i e s w i th a m a s s s p e c t r o m e t e r a n d on d e v e l o p m e n t
of a double oven for s tudy ing f r a g m e n t a t i o n a n d d i s s o c i a t i o n
r e s u l t i n g f r o m i o n i z a t i o n by e l e c t r o n i m p a c t . He t e r m i n a t e d
a t A N L on D e c e m b e r 19 , I 960 to r e t u r n to t h e L a b o r a t o r i u m v o o r
M a s s a s p e c t r o g r a f i e , A m s t e r d a m , the N e t h e r l a n d s .
D r . M a l c o l m M a c f a r l a n e j o i n e d t h e P h y s i c s D i v i s i o n a s a R e s i d e n t R e
s e a r c h A s s o c i a t e on N o v e m b e r 2 , 1959. He s t u d i e d s t r i p p i n g
r e a c t i o n s a s i n d i c a t o r s of t h e s t r u c t u r e of l igh t and i n t e r m e d i a t e
n u c l e i ( P r o j e c t s V - 9 a n d 1-22) , p a i r i n g f o r c e s in n u c l e i , a n d , in
57 c o l l a b o r a t i o n wi th R . D . L a w s o n , a r o t a t i o n a l m o d e l for F e
He t e r m i n a t e d a t A N L on D e c e m b e r 3 0 , I960 t o jo in the P h y s i c s
D e p a r t m e n t of the U n i v e r s i t y of R o c h e s t e r .
Recommended